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Old 01-06-2005, 09:09 PM
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Inaccurate car manufacturors mileage ratings....what can be done?

Hey guys,

Some of you may have read my post about my new truck getting bad fuel mileage. After talking to the dealership, they say there is nothing wrong and nothing they can do. Another dealership told me that it is not a warranty item. Since then I have driven real easy and the speed limit and still can not even get close to the rated mileage. It is suppose to get 19MPG on the highway and will only get 16-16.5 with easy driving at 70MPH. My old truck with the same drive trane package exactly would get 19-19.5 under the same conditions and had the same modifications(air filter and exhaust)

The truck has 4 O2 sensors that are used for a blended AFR reading to control the closed loop operation of the engine. I believe that one of these sensors is slightly out of range and likely causing the problem, but I have not way to prove it and the dealership is not willing to check this.

The question is what are the damn ratings good for? Is there anything that can be done when a vehicle is way off on the rated mileage? I have not been able to find anything on the net.

Any info is appreciated.

Thanks,

Chris

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Old 01-06-2005, 09:15 PM
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I've seen a lot of new rigs that don't measure up, in the gas mileage department. Once the break-in is complete and you've logged some 10,000 miles on that new truck, your mileage should improve some.
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Old 01-06-2005, 09:30 PM
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lol, that happens with EVERY new car. Its because gas mileage ratings have nothing to do with the speed limit on the highway. IF you go 60 I'll bet your gas mileage goes up 2 mpg at least. Most gas mileage reports are based on 55-60 mph.

K
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Old 01-06-2005, 10:30 PM
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Nothing wrong with the car, its you! If you would just drive along at 45 mph with A/C off and never stop you will get 19 MPG.
Actually that rating is a comparison rating. The manufacturers will run their vehicles thru a preprogrammed set of mileage tests on a "real life like road test" thru city and highway conditions which dont include warm up cycles and traffic congestion. I used to do mileage tests at the Linc/Merc dealership which consisted of preset speeds to verify what the maximum mileage a car could get. I could get 34 MPG in Lincoln Town Car any day of the week, but that was only after the vehicle was warm and if I hit any traffic lites I would have to start the test over again to get the mileage verification of 34 MPG. That test is to confirm what the vehicle is capable of getting and that is how that 19 MPG rating on your truck is compiled. AND ... the government just goes along with that.... cuz their stupid and they are the government!

The oxygen sensors before the cats are normal 02 sensors that tell the PCM what the engine is doing and cycle at a high rate of speed. The sensors behind the cat are the cat monitor sensors that cycle much slower if the cats are good. When you have a bad cat the rear sensors operate at about the same rate as the front ones and that tells the PCM to set the check engine lite because of the bad cat. If there is even a minor problem in the system the lite will come on and the PCM will set a code. With no lite on, the system is operating within acceptable parameters, which are very narrow in todays cars.

Last edited by 2-manytoyzs; 01-06-2005 at 10:45 PM.
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Old 01-06-2005, 10:47 PM
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It will get better as it breaks in, make sure the tire pressure is at the rated max and the air cleaner filter is spotless. A couple of mpg is nothing to make a stink about, it can easily be attributed to driving habits and other variables.

Since when did you ever trust a mfg to give accurate/realistic mileage ratings anyway Turbo?
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Old 01-07-2005, 06:54 AM
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Originally posted by 4 Jaw Chuck
Since when did you ever trust a mfg to give accurate/realistic mileage ratings anyway Turbo?
yeah man, 'sup wit dat? screw the mfg.
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Old 01-07-2005, 07:39 AM
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Having bought 14 new vehicles, NOT ONE has met the window sticker for milage. I-90 (Thruway) is relatively flat from Syracuse to Buffalo. I set the cruise at 62 mph in almost every one of them to see what vehicle would be the winner. Everyone runs 70 plus, so imagine my disgust, being blown by, by a Yugo carrying 5 people stuffed in it... BUST ! It felt like I was a one car funeral in every single trip.

Your milage may vary!

I kept complaining about my 01 Silverado. They reworked the computer, and I picked up about 2 mpg. Ya gotta keep whining!
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Old 01-07-2005, 08:45 AM
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Hey Chris,

When I was dealing with GM they kept stonewalling me. I called the number in the owners manual and got nowhere. It was after I called the better business bureau automotive line that I got some satisfaction.

Funny side note when I called the BBB they had a pre-recorded message that said something like: " If you own a Jeep Cherokee press 1, any other vehicle press two".

Keep after them. The squeaky wheel gets the grease.

John

Guys, he had an identical truck before that got much better mileage with the same driving habits, so something isnt quite right.

Last edited by propaniac; 01-07-2005 at 08:59 AM.
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Old 01-07-2005, 08:53 AM
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John's right the squeaky wheel gets the oil.


Rather than it's not getting what the sticker says it should. I think Chris's complaint is more that the new truck gets 3 mpg less than his last one, which was identical size and drivetrain wise to the new one.
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Old 01-07-2005, 09:11 AM
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Yep, my complaint is with the fact that my old truck would get the mileage if I drove 70 straight highway. I drive alot for my job so I can easily get 100 straight miles of highway with no stops and the truck starting warmed up. Best I can get is 16.5.

The truck has 16,000 miles on it so the break in thing is a moot point.

As for driving habits.....if I drive the crap out of it, mileage is 13 in town and 14.5 on the highway. My old truck never got below 15MPG even driving it like it was stolen......which I do.....alot.

I suppose I will give it till 20,000 and see if anything changes, but I am not holding my breath. I think I will call the BBB and see what they have to say as well. There is something just not quiet right.

What really ticked me off is when I went in to talk to them they said my filter, exhaust and 18 inch wheels make it impossible for my truck to get the right mileage and all of those will make it go down. Bull$$&*!!!! Filter and exhaust got me 1MPG better on my old truck on the highway. The 18 wheels and tires are aluminim lower profile and are lighter than stock. Roll out is within a few inches of the factory tires, so that is not the problem.

Chris
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Old 01-07-2005, 09:20 AM
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Quote:
Originally posted by TurboS10
What really ticked me off is when I went in to talk to them they said my filter, exhaust and 18 inch wheels make it impossible for my truck to get the right mileage and all of those will make it go down. Bull$$&*!!!! Filter and exhaust got me 1MPG better on my old truck on the highway. The 18 wheels and tires are aluminim lower profile and are lighter than stock. Roll out is within a few inches of the factory tires, so that is not the problem.

Chris
When they say something like that you have to stick it to them.

Put the ball in their court, ask them to inspect the truck, do whatever tests they need to do. Ask them point blank "is this truck capable of getting the advertised mileage, can we agree that it is in proper care?"

Show them your service records if you have to.

"so you're saying if I put a stock set of tires and filter on this truck, I'll get the MPG that was advertised when I bought it?"

Make them responsible for their statements, and hold them to it.

K
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