Porsche 996 reliability - let's get better info

I wanted more up-to-date car reliability information that included actual repair rates. So in late 2005 I started getting people together to make this possible. TrueDelta now updates actual repair frequencies, not just dots, four times a year, to report on new models sooner then track cars closely as they age. With 350 owners signed up to participate so far, we've started providing reliability stats for the Boxster and Cayman. I would like to do the same for the 911. Just a matter of getting enough owners involved. So I'm grateful to this forum for giving me permission to post about the survey here. To encourage participation, participants receive full access to all results, not just those for the 911, for free. I'll share results, once we have them, in this thread after each update. For the details, and to sign up to help out: Car reliability research Update: Sorry, I didn't have automatic notification turned on, and so wasn't aware of the following responses. My detailed reply is in post #39, on the third page. The short version: I had formal permission to post here, the sample size will be sufficient, and the methodology is sound.

Despite your good intentions no conclusion that you come to with data gathered here is statistically significant and you would need a larger sample size for any conclusion to be valid. You are wasting your time and effort in order to come to a flawed conclusion that will only mislead - regardless of the conclusion that you might think that you have come to.

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Agreed.

A nobile quest for sure. But you are going to need info from dealers.. 350 owners is not going to give you what you are looking for. ESPECIALLY from the internet. Most people got here BECAUSE of problems that they wanted to find a cheaper fix for.

As Kyle said, the only way to get statistically significant data is to tie into the dealer network and get real data and to be honest if they disclosed that data without the permission of the owners, then they would have to deal with significant privacy issues. I'm pretty sure the OP knows that. In re-reading the OP I really do wonder what the purpose of this really is. Looks to me like this is just another sales effort.... a commercial enterprise doing a half-assed job trying to look statistically significant when in fact it's neither well intentioned, or founded on a significant database. This is about money and no other purpose. This kind of post is not welcome and does not serve the members of this community, it only serves the commercial goals of the OP.

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+1

Well put guys. I had a similar feeling about Mr. ( ) Raby's posts. Seems as if he has left the building.

I have a book full of receipts that can give you DETAILED information about reliability of a 2002 996 C4S! It's a small sample size, but hey, it's something! Based on my data and sample size, there is a 0% IMS failure rate in the 996. Great news!

Regardless of statistical significance, this "study" by design has the lowest level of evidence possible (5), with significant bias. Not something to intelligently base an opinion on. But, I'd imagine most people these days don't care to look beyond the first thing they hear, so there's probably an audience out there for this kind of work.

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When I was looking at 996s before there was an IMS retrofit kit, people were talking about D chunking of the cylinders, the RMS failures, etc. IMS was almost unheard of. A few months after the retrofit kit went on sale, it's all people talk about on the forums. My personal and professional experience has so far shown the 996 to be an impressively robust platform, but that's neither scary nor sensational...

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Pete, I assume you're referring to Wellardmac's comment: Pete, that's a pretty harsh statement for someone who actually does provide a useful service and make useful products we can use to further the enjoyment of our hobbies.

Ihad someone call my car exotic the other day.... I dont see it as such. but if it is.... for an exotic its realiability is fantastic. You ever been on a F or L forum.. THEY gots little nagging problems

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I wasn't meaning your statement was harsh, that's why I addressed my comment at Pete! My take regarding Raby is that he sells a part that fixes a broken part! If yours breaks, he has something to fix it. I've never read his site, but I've read his threads on here which Pete was referring to. Doesn't Raby's site advertise the products he sells? I'll have to go check it out, but I'd imagine it's pretty clear he is selling a product to fix a problem.

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Apologies for the misunderstanding. I deleted my message. We've had too many of these scaremongers pass through and ones like this one that come here to plug their enterprise (against rennlist rules) annoy me no end. Hopefully he's gotten the message that he's not welcome.

Let see.... if I 'give' my data they 'charge' me to see the results? No thanks..... and I'll echo what has been said: most Porsche owners don't spend time on the internet talking about their cars, unless they are enthusiasts or have a problem with their car - which skews the results. The 996 in particular sold in great numbers so to get accurate data you have to have a good percentage of them included.

Wellardmac again expresses my sentiments exactly. What put me over the edge was the all the 'IMS' issues he would comment on. No doubt Raby is one heck of knowledgeable guy. But when I read a post from a guy who was just about to pull the trigger on his own 996 only to be frightened off that really turned me off. The only posts I ever saw from him were regarding our cars blowing up and what product could be sold to fix it.....nothing about chiming in a 'summer drive' or 'what blast it was to own one of these cars'. I actually posted an observation one time and it was responded with 'please close this thread'. That told me the truth about what was happening. Simple as that.

I've found my car to be ridiculously reliable, despite two previous owners and some hard use. The list of things that have straight up failed in 100,000 km is very, very short. Combine that with less than $5000 a year in depreciation, and I'd have to say the most expensive part of the car is the nut behind the wheel. Mods, baby, mods. What costs the money in a 996 is not what you need to do, but what you want to do...

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Yup, I've got to agree 100%. I wish all of my cars were this reliable. I've been amazed at how solid my car is.

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Curious about this. Can you post what you are referring to? Thanks.

If people like Raby were not around to post their experiences and a method to fix problems, we'd be left with posts about everyone having problems and nothing to do about it. It's quite nice that there's a fix for one of the known issues with the 996 engine, isn't there?

Agree. A strong aftermarket doesn't have to be likable. It just has to be there.

I like Jake and the service he provides. I don't think the guy would go out and develop the IMS retrofit for some phantom problem on his own dime and then scaremonger folks into buying it. That borders, quite frankly, on ludicrous. Having said that, I don't see how this unscientific survey could provide any meaningful information.

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PM sent to Paul. Sometimes its best to let sleeping dogs lie.

This is a pro LN Engineering/ Flat 6 post The newbies around here forget that the IMS bearing issue existed long long before the LN IMS Retrofit came about. Also, without Flat 6's contributions we would not have a way to run a remote oil filter, remote oil cooler or add an accusump to our motors. Jake see's a pattern of problems and tries to figure out a way to head it off. I have spoken to Jake about transmissions when I was in need and it was too soon in his development but he new exactly the problem that I described to him. I have held a few of these broken and failing IMS bearings in my hand. Enough of them to realize that cheap preventative insurance is to replace the thing before you reach the failure mode. I for one am happy that there are now solutions available to us for preventing our motors and transmission from self destructing. I have now had one each of those go and you can be certain that I am taking every precaution I can on my 996 and 986 going forward now that I have the choices. my 2 cents.

I am surprised at the reactions posted here. Michael Karesh is a very serious guy and his True-Delta data is highly respected. He knows statistics, and can handle the unhappy owner bias. I'd like to see 996 data on his site if only to prove that the car is very reliable. Why a few of you seem to think it would do otherwise is a bit odd isn't it?

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It's simple Bob, there's no way that he can get a statistically significant population of Porsche owners to make any of his conclusions valid. It really is that simple. The fact is that if he were to recruit every member of this site (ever single one!) he still would have a biased population, as he would only be capturing the enthusiasts and ones that might be biased towards having issues with their cars. The only way to get a truly significant population is to have a large enough sampling of RANDOM porsche owners willing to participate in his survey.

I just want to add to my post above to put things into perspective. Porsche sells a total of approx. 100,000 cars per year. Porsche claims that two thirds of all cars they have ever built are still on the roads - that's a hell of a lot of cars. Rennlist has a total membership of 79,000 - most of them inactive. PCA has approx. 100,000 members, most of them inactive. So, even if you were to get responses from all active Rennlist members and all active PCA members you would capture data from only a small section of Porsche owners. You *might* (assuming that PCA members and Rennlist members have not self-selected into population by virtue of their enthusiasm for their marque, which as we all know is a false assumption) have a sample that is representative of "Porsche owners", but not a sample that is representative of any given model or model year, so to try to capture an even smaller subset of that (say, 996 owners) and try and work out reliability data on an admittedly small and self-selected subset of owners is a flawed endeavor - that's even before you try and segment even further by model year. I'm not being mean here, I'm just pointing out the reality that any numbers gathered from a small self-selected group are inherently flawed and worthless. Anything meaningful would have to be gathered from a random selection of ALL Porsche owners and not ones that have self-selected to any particular forum or club. The reality, as others have said many times, is that the only entity that knows about Porsche reliability is Porsche themselves.

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You sir are a voice of reason, well said. What it boils down to, is a wide demographic that these cars exist in, a 10yr old porsche is in an entirely different demographic than a 1yr old porsche(for the most part). Point in case, I earn 1/3rd of what the original owner earns, I can turn a wrench and dont mind getting my hands dirty, he has never turned a wrench in his life. I am also less than half the PO's age. And now on top of this trying to gather a wide array of data from a wide array of Porsche owners, few 996 owners post here or have even heard of rennlist, my neighbor down the street has a 996(2005) and has little or no interest in rennlist. With that said it IS a noble effort but, I feel a noble effort in vain. Now too Mr. Raby..... After reading I cant recall how many pages of IMS failures and IMS installs (Kyles was very good BTW), Im sick of it to be honest. BUT with that being said I am glad that I am aware of the issue and the fact that MR.Raby has designed and provides techinical support of the issue. The IMS issue is kind of like that ASPCA commercial with the sad music and the abused animals....you get upset....but its easier to change the channel and know that your pets are in good hands. Does that make sense...or am I rambling like a bafoon?

Makes total sense to me. mkaresh don't forget to go back to all the persons and find out how much of the work/billing done on their cars was not needed and how many times they got billed before the actual problem was fixed. Then bounce it around with the Porsche dealerships performance in the area of getting the diagnosis right the first time. From what I've seen online is taking the car to an honest Porsche dealership is the only way to go unless there is an alternate porsche mechanic that works wonders. For me if the engine quits in an ugly manner its upgrade it to be a beast of some sort or just throw another engine in from good old Duetchland. I don't care to know what the run of the mill is up to. They can get recycled with the aluminum cans and water bottles

Those who developed retrofit kits are quite good for people who want to increase the reability of the engine, but It's a critical way to go if you're a rennlist active user... It's important to separate the internet information and help, and the real business. I purchased several parts to J*** and did a lot of advertising and publicity in my forum (Soloporsche), but when I'd need to ask 2 important questions, about the IMS operation, there wasn't any reply from him. That's why I'm a bit dissapointed , because if someone's "helping" or sharing info, It would be better being more kind. I'm happy to learn about several points referred to 996 engine in those enterprises but It's a delicate business share info in a Porsche forum. When you risk to sell your pieces in a forum you are exposed to all kind of critics (positive and negative) Internet Forums were born to share information not to make business Here you can see several pictures from a soloporsche motor engineer who is trying to help those who want to reinforce the IMS parts and could get it done by an expert lathe operator, as I did, copying the idea from our soloporsche friend who did by himself last year without searching anything. He doesn't apeak english, he didn't Know LN Eng , he'd never been here, but he tried to use the logical reasoning to do the operation... He opened our eyes and I got it done by my mechanic .

Nice post Joaquin! Now this is why we have forums. Looks like nice CAD work from your engineer buddy. Very robust looking solution. What is the upgrade to the actual bearing itself? Phil

I used an increased F125 steel bearing support. Here you can see the differences between OEM 8 mm and custom made (12 mm): SKF hybrid steel / ceramic ball bearing: SKF bearing = 155 € = 210 $ Lathe operator bearing = 50 € = 68 $

Lathe operator bearing = $68 12mm custom made support $63 actual bearing cost $5 I assume this is close to an actual cost breakdown. I'm basing this on doing these type of conversions myself in my line of work. I have my own machine tools and I purchase a lot of bearings also.

Holy cow! Wish I spoke Spanish..

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Sorry if I didn't explain correctly... I mean: Lathe operator labour bearing support 12 mm steel F125 = $68 Hybrid bearing from SKF = 210 $

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Thanks for explaining it, WOW! that is a hybrid bearing. I thought somewhere it was mentioned that a Vespa scooter bearing was used. Also, FWIT, if the support and housing is being made from scratch it seems a non proprieraty could be used. Thanks!

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My mechanic posted the whole operation in a website and as he is very funny and ironic, he told that Vespa's motor wear a similar bearing. this is which I used: SKF reference: 6204-2RSLTN9/HC5C3WT http://www.skf.com/skf/productcatalo...bleName=1_23_1 (You can see 3D view) Both bearings with their support (left OEM, right custom made/SKF)

An update.......Article by OP....published regarding JD Power Associates 2010 VDS. http://www.thetruthaboutcars.com/the...bility-survey/ Interesting.....

Sorry, I had no idea these responses were being posted. Either automatic comment notification is not available or it is not turned on (I'll check after posting this). The negative posts in this thread, the ones directed at me at least (it seems to have gone OT), follow from misreading / not reading what I wrote, insufficient knowledge of statistics, and more than a touch of cynicism. --I obtained the formal permission of rennlist to post here. This is noted in the OP. --I worked the first four years on this at a loss, and continue to put in far more hours than can be justified by how much it earns. Anyone who has started a project like this from the ground up and then worked to get thousands of people involved can imagine what I've had to go through. Others, perhaps not. Saying that I'm conducting this research for some underhanded reason without any basis for saying this is simply insulting. But then I've learned that if you don't want to be insulted without cause, don't post in forums --I don't ask people to pay for results they've helped provide the data for. I explicitly state in the OP and on the site itself that anyone who participates gets full access to my site for free. Let me repeat this, in case it was missed the first time: participants get full access for free. That's free, as in no money. Some people manage to read the opposite, but I can only control what I write, not what people read. --The size of the population has absolutely no relationship to the necessary sample size. It's not even part of the formula. This is statistics 101. Larger sample sizes are certainly always better. But 25, and sometimes even fewer, can certainly provide useful information. --The survey process was designed to deal with the problem that people might join because of the problems they've had with a car. And it has been very successful in dealing with this problem. For one thing, it collects data going forward. Past problems cannot be reported on the main survey, and so cannot influence the results. --People charge all of the time that the survey will just be based on people who want to complain. Fact of the matter is, we have some car models for which over 90% of car owners report no repairs at all in the past year, and for the average car model over half report no repairs at all in a given year. So I think we can consider the "complainer hypothesis" rejected. --Data from dealers wouldn't be of much use unless you knew how many cars this data COMPLETELY represented. This might not be possible. Better yet would be warranty data from the manufacturer. But it doesn't matter, because dealers and manufacturers aren't going to provide this data. --If I have to choose between some ideal that simply isn't going to happen and a possible, practical alternative, I'll go with the latter. It's the difference between talking and doing. --I'm well aware that not everyone cares about reliability stats or wants to participate in something like this. I conduct this research for people like myself who are interested. If anyone seeking to help has made it this far into the thread, you can read more about the survey and sign up here: Car reliability research

I'm not sure why everyone if flaming mkaresh & jumping to these conclusions about validity. You can't declare a survey invalid if you don't know all the details about the goals of the survey. Sample size is not the be-all end-all of whether a survey is valid or not, depending on what they're trying to accomplish. For something like a national opinion political survey, a representative sample of all constituents from all 50 states would be important. Having such a population might not be so important if the survey was designed to measure the reliability of, say, aging porsches owned by enthusiasts who post on the internet a lot.

See post #27 and you'll see why no matter what the OP says, the endeavor is still statistically flawed.

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AND YET, it is the entire business model of Consumer Reports auto reports. And most people believe CR to be the gospel truth! I say good luck to the survey.

+1 The main issues here are that respondents self-select, and that they self-report over time. The latter is a bigger deal than you might think. Just ask A.C. Nielsen what happened to television ratings when they switched from diaries to people meters. By the way, the OP's comment about sample size might have been a bit flip. If I assume a population of cars somewhere around 200,000 and a study sample of 25 people as he suggests, the margin of error would exceed 20%, 95% of the time. In other words, if five people in the sample had their ronky booboo valve fail, the projected number of failures for the total population would be anywhere between near-zero and 80,0000 units. You see the problem

A much better solution is legislation that requires automakers to give up their internal data. With the recent Toyota situation, combined with the current administration's tendencies, I wouldn't be surprised to see something like that in the future.

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The self-selection is not a major factor if you collect data going forward, word the survey as objectively as possible, and keep the load light enough. Nielsen's survey required too much of participants. And, IIRC, the main thing that was discovered with the people meter is that people used the bathroom and so forth during commercials. Shocking, I know. I'm not saying a sample size of 25 is ideal. I'm saying that at that level you do get a viable indication of how often cars require repairs. I would not attempt to measure the failure rate of a specific part with 25 people. It's easy to trot out hypotheticals. Here's what our current results look like for the Boxster, in terms of repair trips per 100 cars per year: 2008: 67, small sample size 2005: 103 2003: 125, small sample size 2002: 167, small sample size 2001: 125 2000: 129 1999: 133 Those labeled "small sample size" have fewer than 25 responses, so they're asterisked and only visible to members on the site. Even then there's only one result out of line with the others, the 2002. The 1999, 2000, 2001, and 2003 are all very close together. I see this over and over in the survey. There are some results that are clearly off, and are commented as such, but these are easily exceptions and not the rule, and don't happen once the sample size is over 50. Do you think this happens by chance? I can guarantee one thing: claiming that the survey isn't viable because of the sample size tends to be a self-fulfilling prophesy.

I can't wait to see my car isn't as good as a honda accord

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It's only a solution if it happens. I'm not holding my breath on this one. Cars would be much better if they performed like a 911 turbo, had the gas mileage of a Prius, and the price of a Nano.

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I'm pretty sure it does at least some things better than an Accord. And one of the main things I try to communicate, hard as communication tends to be, is that even when a car is "worse than average" we're still usually talking about less than one repair trip a year. Few people realize how low the average is, because no one else has been providing the actual repair frequencies for each model. Dots lead people to think that the differences between cars are larger than they actually are.

"See post #27 and you'll see why no matter what the OP says, the endeavor is still statistically flawed. " Post 27 was the post I was specifically responding to. Not all surveys are the kind they conduct in college psych classes. Not all surveys try to accurately predict the number of xyz valves that will fail. Some just try to get a general direction - up or down. For example, if the survey included something along the lines of average mileage between from rear tire changes, you'd get quite a variance, but you'd probably see a good cluster (likely under 20k miles) wiith a few outliers. While I agree that this not this would pass muster at a in the legal or academic world, it would likely agree with the user-experiences I've seen on rennist & might be helpful to other 996 owners or prospective newbies.

With the current sample sizes, the goal is in between those two extremes. I'm not about to claim that we're measuring repair frequencies within 5-10 repair trips per 100 cars. But we can say whether the frequency is roughly 30, 60, 90, 120, or so forth. I have a Ph.D. from the University of Chicago that involved a fair amount of training in survey research and statistical analysis. There's a chance I know what I'm doing.

If you have a 911 then you might understand only compairing it to other cars that take in town turns at 30-40 with hardly ever a squak from the tires. Kind of adds to the abilty to take wear and tear in all departments. Then the total revs are generally the life span of an engine with the high revs giving birth to faster wear and tear. I kind of wonder how a stock 911 would hold up in a stock car race. It would be kind of funny to see a porsche at daytona. Might be too insulting to detroit engineering to run a bone stock car and clean up. I'm sure the racers commo would normally be traffic like "save me baby jesus!"

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You're dealing with a group of people that is very sensitive to bad and anecdotal public information about their cars, so you're going to be held to a higher confidence standard than whatever you think is 'directionally valid' (a term I've heard about a million times in 30 years of working with market research, and which usually follows some kind of wild-*** observation based on a fragment of questionable data). If you're experienced with this stuff, then you know that every additional compromise in the sample design multiplies the degree to which confidence is reduced. You have three: A potentially questionable sample, plus a self-selecting sample, plus longitudinal self-reporting. Any one of these is an asterisk, but all three is sketchy. The last thing anybody here wants is a piece of data that misrepresents the cost of owning a 996, but which floats around out there on the interweb doing a great imitation of fact. You should expect a little heat, and not be too dismissive, IMHO.

Where did I say anything about "directionally valid?" Have you looked at the actual results, and found them questionable, or are your arguments based on textbook theory? I'm aware of the factors you mention, and have been pleasantly surprised by the quality of the actual data. Results could have ended up all over the map. They have not been. It does help that I selected a metric to minimize variance, and am not relying on respondents to report much beyond whether or not the car required and repair, and whether this repair was successful. I'm well aware that many people would prefer no results to a result they do not care for. I have not found a good way to respond to this. I personally prefer imperfect information to no information. In the real world, perfect information is rarely possible. Ironically, I started trying to get more Porsche owners involved because Porsche owners kept contacting me to.

My arguments are not based on 'textbook theory'. I'm not the one who trotted out his PhD. My arguments are based on decades of experience in interpreting market research to advise corporations on making multimillion dollar bets. That's about as 'real world' as it gets. To your comment about imperfect information, I didn't say that people objected to information they don't like. I said they objected to information that is misleading, which is a risk here.

In your experience advising your clients, are they much more likely to question a study when they don't like the results? You keep bringing up what might happen. I've been conducting this survey for four years. Can you find any actual cases where people have been misled by my results? Which of the current results do you feel are likely to mislead people? Here's the full list of the latest stats: http://truedelta.com/latest_results.php A few seem off, and are commented as such. This has been much more likely among older cars, I suspect because people start living with problems rather than fixing them. But the great majority of these results are internally consistent and consistent with the results from other surveys. Just with actual repair frequencies, not just dots, and on average nearly a year ahead.

No, you're absolutely right. I can't name a single person that has been misled by your results. Therefore, they are immutably true. (This same logic was used to great success in reporting Polish crop yields to the Soviet government.) Dude, seriously. That's a pretty lame response. As is the fact that your research is validated by its resemblance to the research of others (raising the question of why it's worth doing in the first place). To answer your first question, my clients challenge research on the basis of its design. I imagine they would be especially skeptical if the data featured banner ads and Google AdSense links. If you're going to use a forum like this to drive traffic to your commercial web site, then I think it's perfectly reasonable to ask you to defend your product... and kind of nice of me to warn you that it's a sore point around here. Anyway, good luck with it.

I did not say that since you cannot name anyone who has been misled, then no one has been misled. Why twist what I said? I was merely trying to shift the discussion from hypotheticals to what has actually been happening. I do not see what Adsense (also the source of any banner ads) has to do with anything here. Conducting this research is more than a full time job for me, about 70 hours a week, and I cannot afford to do this for free. The advantage of Adsense is I have absolutely no direct contact with specific advertisers. I mentioned two key advantages over other studies in my previous post. To repeat: 1. Actual repair frequencies, not just dots--which often ACTUALLY mislead people because few if any people know the repair frequency represented by a dot. So they assume inaccurately. 2. Updated promptly four times a year. Consumer Reports and JD Power currently provide results based on surveys conducted back in the spring of 2009. My current results are based on data through the end of 2009, and will soon cover through the end of March 2010. Would you prefer to know how a car was doing a year ago, when it was a year younger with 12,000 or so fewer miles on it, or how it has been faring recently?

Thanks for your efforts mkaresh - I have been a member on your site with 3 of my past cars, and now with my Porsche. I wish there were more people joining. In fact, after getting a results email from you today, I went to the site to check on Porsche, and saw the note about not having 25 people. I then came here and posted a note to join your site, and then immediately after posting it I saw this thread

Thanks for your comments Bruce - common sense as usual. Honestly, how anyone can think that such a small and unrepresentative sample of Porsche owners is worth any more than a steaming pile of BS is beyond me. No-one is against having good data, but the point that we're making is that mkaresh doesn't have good data at all and is pretending that he does and IS misleading by pretending otherwise. This does no service to anyone.

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Thank you for helping me provide a steaming pile of BS I have no doubt that Bruce is very good at what he does, which is critique the work of others. Anyone who has ever tried to create something knows that the task is much harder than that of critiquing it, and that there is never a shortage of critics. I am aware of no better publicly available reliability information than the information I am providing. Anyone who thinks they can do better, I invite you to give it a shot. It is clear to me that the sample sizes are the #1 weakness of my results. As we get more people involved--over 2,000 join each month--this weakness will go away. We already have sample sizes over 100, even 200, for a few cars. I look forward to doing the same for nearly all cars. So I hope anyone interesting in actually doing something, rather than saying what can't be done, will join and help out.

Guys, this is not worth even discussing. The OP (which he and I have discussed this at great length offline several weeks ago) is looking to do something in the form of a self-report survey for car owners and informed the forum about it. It should have been left at that. More of an announcement if you will. Whether it's a disgruntled owner wanting to feel "misery loves company" or a highly trained academic in statistics (like myself and the OP) trying to collect data, the simple fact is that the responses in this thread are the same as all the other threads........over and over and over again. It's going to get nowhere. As one who enjoys crunching the numbers as much as the next stats geek, we are going to get nothing from this thread (like all the ones before). IMHO, this thread will do nothing for either side of the debate. The OP and I will have to agree to disagree on the validity of the study and the significance of any conclusion drawn from it. Nonetheless, I wish him well in his endeavor.

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Always fun when things get personal. Anyway, since you don't know me, you can be forgiven for the absurd irony of that statement. I've created quite a lot of things, actually, including some things you've probably heard of. And I can tell you that if you're going to make a living 'creating things', you have to expect to defend your ideas sometimes. I don't care if your name is Spielberg, it goes with the territory.

It wasn't my intent to make things personal. I truly do not doubt your expertise. The problem with defending what I do in a public forum is that the more detailed responses in such a debate get, the fewer people sign up to participate. Since the quality of my results is heavily based on the number of participants, such a debate ends up being a no-win situation for me. But this thread has been rendered ineffective for me at this point--there now aren't likely to be stats for the 996 any time soon, mission accomplished for anyone with this objective--so might as well debate on. Here's an example of my results, for the Audi A4. Stats in terms of repair trips per 100 cars per year (lower is better): 2010: 30 2009: 64 2008: 48 2007: 48 2005.5- 2006: 78 2005: 154 2004: 135 2003: 119 2002: 159 Is there more information here than can be found in a steaming pile of BS? For me, a lot more. I see a very clear difference between the B6 (2002-2005) and later generations. I also see higher repair rates for the first model year of each generation (2002, 2005.5-2006, 2009). The 2005 is a little higher than might be expected, until you realize that these cars were in the last year of their standard warranty--when people rush to get minor repairs done that they've been putting off. I see this "final year of warranty" blip often, especially for German cars. I recently started providing a second set of stats that reports, unlike anyone else, the percentage of cars with no repairs in the past year, and the percentage with 3+ repair trips. These stats, especially the latter, require larger sample sizes than the average repair frequency, so I have them for fewer cars and advise against reading too much into the "lemon-odds" until we have more people involved. The percentage of cars with no repairs during 2009 from the first eight cases (alphabetically, not cherry picking) where I have these stats for at least two consecutive model years: Acura MDX 2008: 70 2007: 53 (first year) Acura TL 2005: 84 2004: 75 (first year) Audi A3 2007: 64 2006: 31 (first year, very common failure with sunroof sunshade clip) Audi A4 2009: 52 (first year) 2007: 71 2005.5- 2006: 50 (first year) BMW 3-Series 2008 335: 53 (common problem with fuel pump) 2007 335: 54 (common problem with fuel pump) 2007 328: 63 2006 E90: 53 (first year, no 335) 2004: 48 2001: 8 (worst among cars for which we have this stat) Buick Enclave / GMC Acadia / Saturn Outlook / Chevrolet Traverse 2009: 74 2008: 53 2007: 41 (first year) Chrysler 300 / Dodge Charger / Dodge Magnum 2006: 54 2005: 46 (first year) Ford Five Hundred / Freestyle 2007: 65 2006: 64 2005: 44 (first year) In all eight cases the stats form a clear pattern, with a lower percentage of cars with no repairs as cars get older, and especially for the first year in a design. Given the sample sizes, small in most cases, I'm been pleasantly surprised that the results are this clean. I would not expect most of these to be accurate within fewer than 10 points, but we're not seeing unexpected variation of more than a few points here. So, again, no more than a steaming pile of BS?

Yes, absolutely a steaming pile of BS. You're trying to extrapolate the results of double or low triple digit responses from a self-selected population to cars that are mass produced in hundreds of thousands of units per year. This is not personal, we (and I know others have also tried and failed) are trying to get through to you that the methodology you're using is grossly flawed. I know that you don't get it and I know that there's no changing your mind, so it's time to move on. I'm not a big fan of wasting my words where there is no chance of reconciliation - It's way more fun and effective to bang my head against a wall.

Why do you feel the need to be so insulting? Is this junior high? Edit: looks like Wellardmac's references to my being "thick-headed" and "moronic" have been removed. Thanks, I suppose. As Bruce can no doubt confirm, when the size of the population is large it has absolutely no bearing on the required sample size. Population size isn't even part of the formula for determining the required sample size. This is stats 101. It's what makes survey research viable--samples are often a very small percentage of the total population. What does matter: the variance. Which is why I initially focused on a metric with a low variance. It's not relevant, but I might point out that few car models are produced in the hundreds of thousands per year. And certainly no Porsche is. Tens of thousands, certainly. I'm aware that the source of my participants is far from ideal. Would I prefer a large, randomly selected sample with a high response rate? Sure. But no one has this, and there's a reason for it. Hard to do even if you have millions to spend, impossible if you need to have low enough costs to provide results to the general public. J.D. Power spends a large amount of money to randomly survey car owners. In return they: --have a target response rate of 23%, leaving them with a high risk of non-response bias, reducing the value of the random sample (the responses they receive are probably not random, even if the people asked to respond are) --have a minimum sample size goal of 225, good, but not as large as many people think --can survey vehicles at only two time points, 90 days and the third year --cannot afford to provide a useful level of detail to the general public I have found that useful results are quite possible even with the sample I do have. And I vastly prefer the results I have been able to provide to no results at all.

Oh Christ..........

Fascinating.

Have you ever noticed why antibacterial soap kills only 99.9% bacterias? Because the 0.1% helps the lawyers win the case. Scaremongering sells. My2002 996 6speed 84000 miles with original clutch and no rms/ims or major problem, so far sensors and a cracked coolant tank for a total of $200 DIY parts. My cousin's 2003 Mercedes SL500 87000 miles has over $20000 in repairs for leaky ABC shocks, flex plate, deff leak, hard top air pump, MAF, brakes, Alarm....etc

Quotes source post: 11391802

Nice math.

Quotes source post: 11391802

Small sample sizes. But I bet a good chunk of that $20k was for the ABC. Suspension parts wear out, and the more complicated the suspension is the more likely it is to fail and the more expensive it will be to fix. Mercedes's ABC system is about as complicated and as expensive as they get. Unless the fancy bits make a huge difference to the car's handling, I always recommend conventional springs and dampers.

I surprised someone hasn't said it yet, "There are lies. Then there are damn lies. Then there are statistics." I rather like my dependable 99 daily driver w/130,000 miles. Not perfect and has busted a few parts, but hey...it's a car. Fix it and move on. I don't need statistics for that and I'm not going to use it. Now for another beer and back to the regular programming. Think I'll head to the garage and check my blinker fluid.....