Cayenne (or equivalent benz etc) Diesel V Petrol

Thought I might put this out to the PFA brains trust.  We've owned a 2011 Cayenne for about the past 5 or 6 years & while happy with the performance & general reliability we have now had two majorish expenses relating to the EGR/pollution control systems.  The first was DPF failure and intake manifold cleaning required due to carbonation.  We've now had a diagnosed failure in the intake manifold valve/butterfly/flap thingy (my understanding it's to alter the intake manifold length for better performance).  In all of these cases the common element is exhaust gasses passing through components and slowly adding carbon....which over time cause that component to seize and fail.  My understanding is that this type of thing is a byproduct of a dirty burn (rubbish diesel here & cars trying to be clean).  So I can't help but wonder if a larger capacity v8 equivalent is the answer (assuming you get a cleaner burn from that type of system).  I love the torque of a turbo diesel but consistent component failure feels like a design flaw (or our crap fuel) rather than general wear & tear. So - can I get some real world l/100km figures on what people are seeing from their v8 2t wagons? @MFX - big benz feedback?  Think I might be swapping out for a v8 in the near future....

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My ML500 is pretty long in the tooth now (2005), but it averages about 14l/100km. It has had a few issues. DON"T get one (or any Merc of that era) with the air suspension. I have had a couple of the shocks fail and due to me not fixing a leaking one for a while I also did the pump. Power wise it is great. It can pull my tank of a car trailer with a car on it up any hill at 120kph without feeling it. Interestingly I am looking at around 2011 Cayennes as a replacement for it, but I was looking at the V8's.

What about a V8 Cayenne? I am becomong increasingly interested in these....

What about a V6? The Merc ones go quite well, my 07 ML350 has more than enough go and uses slightly less than the 500 (12 to 14). The W166, about 2012 on is direct injection which was more power but uses 20% or better less fuel. No major issues with mine.

v8 Cayenne is definitely in the mix - just curious to see what type of increase in thirst we can expect.  Thanks @ANF for the v6 merc thoughts.  I've found in the past that v6's have had to work pretty hard & while fine while cruising, the around town experience in this area saw ours up around the 20l/100km (but have not tried a merc v6 so happy to give it a whirl).  Food for thought.  Thanks @MFX for the input (& fyi we've found our 2011 to be perfect in every other respect...I can just see the diesel thing annoying me into the future).

@Russ has been running v8 Cayenne for a while. i think any modern car is a crapshoot beyond 5-6 years old.  All the emissions related designs seem to have flaws - direct injected clogs with carbon, diesels clog up the particulate cleaning tech.  The underlying powertrains seem to be reliable but all the systems hanging off them cost big bucks to fix.   Same as the old CiS really.

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I have to disagree on both counts. My 13 year old ML has been great and my CIS 928 has cost bugger all to get right. (but I will concede there is potential in a newer cars for things to blow out....) The direct injection ML has 225 kW, but if you want more the newer ML400 or GLE 400 have prodigious power and torque for the same economy, if you are happy to go turbo.

Consider an older generation BMW E 70 X5 50D.  I had one for a while and it was great on all fronts.  Towed race cars and assorted stuff on a trailer that was used for earthmoving equipment (true story). All up just on 3T.  Great economy, nice interior and I think still a nice looking car.  Price about 40-50k I know but one for the list. Also have a think about the Ford Ranger 5 cyl 3.2.  I drive one as a daily and use it to tow race car stuff.  Wildtrak is good because of the extra fruit.  XLT is also good if it’s got the comms pack. You can get good used ones at reasonable price points. If you’re after covered load space, put a cab over the tub. There are also some Tickford enhanced used ones out there. A good used Raptor is one to consider but the lower towing capacity due to the coil rear suspension might be an issue for some.  The benefit on the Raptor is that it’s really nice on the inside and looks wise you can channel your inner Baha ... ... and just to balance out my declared Ford bias, new Colorado’s will be going VERY cheap in the next 2 months.  They’re also a good option.

My ten pence worth, I get around in a 957'S the 4.8 as a daily, averages in the 14s per Lt everday and down to 11s on trip. I believe 2nd gen cars 2011 and beyond would do better.

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I’ve got a current G05 X5 M50d (294kW/760Nm) and it does 8 - 8.5 L/100km consistently on the commute and day to day running around . On freeway and cruisey runs, it drops into the mid to high 7s. Astonishing economy coupled with stump pullin g torque, awesome tow vehicle, does 0-100 in low 5s and for a 2 tonne truck it handles bloody well.  If the E70 shares these attributes for 50k sounds like a winner. We also have an F15 X5 30d (190kW/560Nm) which is a great car, does mid 8s all day long and we’ve towed a 2.4T van or race car and trailer all over the place for years, so far we’ve done 120,000 from new without one issue.  They’re available from 35k or so.......bargain. petrol V8...... 👎🏻

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Hadn't thought about the CIS relationship - that's true enough. Wifes car so unfortunately the dual cab ute is out (& defender does the towing duties so no consideration there).  Will check out the x5 approach but will probably lean to 8's.  Maybe, as Coastr says, they're all the same one way or another.  Just have the shits that an otherwise solid car that feels like it will go forever keeps having wobblies associated with emissions based equipment.  I guess that's just modern cars (you know you're getting old when...) Some tasty numbers there. Good to know - thanks.

The D40 Nissan had these issue's. I was able to block the egr with a stainless steel plate without throwing codes and add a catch can to the pcv. The downside to blocking the egr is having to clean the gunck out periodically that builds up behind the plate. No more muck in the intake and no more dpf failure though.

Correcting the record - having now had the necessary work completed it seems a bunch of plastic residue/packaging (bits of plastic of some description) was caught and clogged in the intake, jamming up the butterfly valve and causing the diagnostics to complain...meaning my little hate on diesels was (at this point in time) pretty much unfounded.  Intakes not carbonated - in fact in pretty good condition & now cleaned.  We now move to the mystery of how plastic pieces (seems it was some sort of wrapping or packaging material) got into the intake system in the first place...

Some relief for you. Red faced mechanic in that shop? "Oh shit, I left that in there last time it was here." Fuel economy may improve too hey.

Ive got a first gen Cayenne TT, averages about 14/15ltrs per hundred and has been absolutely bulletproof over 10 years or so

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First time in this particular shop so easy out for them - 'some idiot......' I imagine the fuel economy may be a bit better (response feels maybe 10% better but I might just be kidding myself)

Good move going to another shop then. 👍

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Been moving around with this one as my regular's preference is for the aircooled stuff.  Think I've found a good service home for it (RPM at arncliffe).