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YOUR RESEARCH14 MPG too low?
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Check fashion way and got 200 miles
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I initially thought my OBC was wrong, but I double checked the old fashion way and got 200 miles from 14 gallons.
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Suggestion
Are you able to fill 15+ gallons from Empty to Full?
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Suggestion
If it's changed over time, you may want to look at things like spark plugs.
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Let me preface this by saying I don't care about MPG in my P-car, except to the extent it's an indicator something is wrong.
I know many 996's get 20+ MPG, but I'm only averaging 14.
I initially thought my OBC was wrong, but I double checked the old fashion way and got 200 miles from 14 gallons.
Granted, my driving style and conditions couldn't be worse for fuel efficiency, but doesn't 14 MPG seem much to low? What could cause this?
BTW - I have a MY01, C4, cab with 25K & recently got new plugs.
Thanks much
Kolshak,
I had a 2001 C4 Cab too.
Around town and daily driving 15-16MPG would be normal (i'd see this diplayed 80-90% of the time). I'd drive so i could hear the PSE roar, so just like you i would guess.
On the way to Thunderhill in the cold morning (top up) i got 26mpg (75-80MPH freeway, no traffic no stops)
On the way back that evening in warmer weather (top down) some AC on 75-80 MPH, little traffic i got more like 23-24MPG
On the track i got 8 MPG
+1. Have never had a car that got such divergent mileage numbers in the city vs. the highway.
You'll get sliiiiightly better mileage if you use premium and avoid methanol enhanced fuels.
2000 C4 tip cab here........ had it since new. it now has 104,000 miles on it. I get just a shade under 25 mpg, average. Always have.
-nice to see someone driving their P-car! Has it been fairly reliable for you?
If you are driving it hard or doing a lot of city driving, 14 is probably about right. If it's changed over time, you may want to look at things like spark plugs.
I always use premium 93, but brand varies.
Virtually all my driving is short trips, around town, stop light to stop light, etc and each trip usually involves high RPM's & some WOT. Thinking about it now, I probably couldn't get worse MPG if I tried.
A consistant 14 seems low, but if thats just the price of admission then so be it....
Kolshak,
I drive EXACTLY like you, and get only 15-16 MPG
I had exactly the same car.
Perhaps tire pressure/brand can make a little difference ??
I wouldnt worry too much.... it sounds normal to me at least
I have a c4s....I average about 15 mpg in town. On the highway...it's much higher, but not too sure how much higher, as I've never really drained a tank on a road trip yet. Keep in mind that AWD is going to guzzle faster.
Sounds about right.
J
With a C4 Cab, I've seen as low as 14.95 and as high as 25.93.. under 15 was mostly around town, probably driving "enthusiastically" from light to light, and almost 26 was on the highway up the mountains.
Mostly 15-17 around town..
I think the mileage of these cars is *really* responsive to how you drive it.
- Nick
I have a C4S and average about 15, but almost all of my driving is in town. I don't drive crazy, but I love hearing the PSE kick in over 4,000 rpm. I'd probably get 18 in town if I wasn't always trying to engage the PSE.
My Avg MPH & MPGs are almost always stuck @ 30 & 14 respectively.
Does anyone know how often or over what period of time the OBC recalculates these numbers and if is their a manual reset?
I almost feel like taking a nice liesurely road trip to see if I can get into the 20 mpg range.
Kolshak: There's a manual reset on your lower left "stalk" below your turn signal stalk. It has four positions and you down or up click to move thru the different functions. You reset by pulling the stalk towards you and holding it till the function zeros out. One of the functions resets your mpg...and it will have an "mpg" designator on it. There is also one for average mph, miles left before you run out of gas, outside temp etc. If all else fails....read your owner's manual....it has a wealth of info in there. I reset mine every time I fill up and, depending upon whether I've been running in traffic or on the freeway, (also affected by how much you stomp on it) I usually get between 18 and 26.
14MPG sound about right for average Autobahn at around 140MPH, other than that seems low....maybe a computer air-fuel mixture problem? I would send Loren an email over at renntech.
Just the opposite experience, here. I find the car gets stunning mileage at speed, and terrible mileage in urban driving. Honestly, I went more than 50% further on a tank over during my last extended 15-160kph run than I do in daily driving in the city.
It's inefficient at low speeds. Built that way, like "a race motor" (quoting Excellence, here). Add the fun-killing adaptive DME into city driving, and it should be no surprise at all that it's a pig around town.
I saw 17mpg for 120mph average at the last Silver State. I'll report back next month on the mileage for 135mph.
I get 18mpg going to work over Topanga, 25+ on a decent run on the freeway, and I got about 9mpg at Buttonwillow on Saturday. 14mpg sounds low, but not impossibly low.
225.3, actually.
Obviously, beyond a certain point, mileage will decline at extreme speeds, what with HP rising with the square of speed. My argument is simply that, within the typical driver's operating parameters, this car will get far better mileage at highway speeds than at urban speeds, and my further personal observation is that the delta is unusually large with this car. Just trying to reassure the original poster that his car is fine.
Very reliable, 'cept for the time it upchucked a tranny....... other than tires, pads and oil, that tranny is the only money I have ever spent on the car (besides mods)..... input shaft bearing **** the bed.
I drove my 928 100,000 miles also...... still have it, semi retired now.
Well said Bruce! I too think he is ok but man throwing in the square root etc... always reminds me of a check ride, yuk!
Oh and sorry I was off 1.7MPH I just did the quick math in my head.
I appreciate the input and agree with your point, however I think I should be getting slightly better MPG. I reset my OBC's average MPG calculation and took a relatively short HWY drive @ ~ 60 to 80 MPH in 6th gear - I could only get a max average of 18 MPG. Even though it was a short trip, wouldn't 18 be my max attainable MPG (under those circumstances), or would it take a longer trip to determine the max fuel efficency?
You need a longer drive to move that number.
Also, the only way to really accurately calculate mileage is to fill the car up, drive it until most of the tank is gone, then fill it up again. But I really do think you're okay. As I said earlier, I've never seen a car with a bigger delta between city and highway mileage. I've also never seen a car with such a responsive adaptive DME function, which I think partly explains this. This is subjective, but it comes from a bit of experience: If I take my car out on the highway for an hour or so after a couple of weeks of urban commuting, the transformation is bigger than I've had 'chipping' other cars. It sounds different, throttle response is sharper, and so on. I've never had a car that liked an Italian tune-up so much. I'm only guessing, but I think the inherent inefficiency of this engine at low speeds combined with the engine controls' aggressive adaptation to driving style is almost inevitably going to give you dismal city mileage.
YMMV, so to speak. All disclaimers about subjective observation, etc...
I got 25mpg on a 2000 mile freeway trip average speed 78mph. My normal commute is on a two lane mountain road with many sharp turns, I rarely get above 15mpg there. If at least half your commute is on the freeway I would expect your mileage to be closer to 17-18 mpg.
