Guys

This is not a Volvo ralated question but it is always nice to hear some feedback about this subject. Due to my job I have to drive alot of rental cars and almost all of them are American(Chevy, Chrysler, Olds, Pontiac Ford etc). Usually almost all of them have low millage but I also drove a rental with 40K.

Based on my experiences I always do some research on the internet regarding the rentals I am driving and I have to admit that the gas millage figures reported in the specifications where ALWAYS way off. For example recently I renter a 5K mile 250HP Chrysler Pacifica which was rated at 20mpg average. Well guess, after I drove the car for 107 miles with 85% of driving in the Highway I got a staggering....15-16mpg. This is a full size van in the vicinity of SUVs and Vans. This is not the only case. I also recently drove a 2002 Buick full size car with a 3.2 engine and I got 18mpg Average. Not to mention that most other American cars I drove were WAY off of the rated MPG ratings.

When it comes to European cars I have to admin that they have very good economy ratings. My brother in laws 96' 325 get 27-28mpg in the highway and 25mpg combined. My 85' 240 gets 25mpg combined.

What is the deal with the American automobile manifactured and how do they ge away with this.

Any opinions?

Thanks

You can't know mileage by driving a car 100 miles. The only accurate way to know your mileage is to measure gallons used between fill ups. The guage cannot be used to get mileage.
--
David Hunter

I always fill up rentals before and after.

"Fuel Economy Guide data is derived from vehicle testing done at the EPA's National Vehicle and Fuel Emissions Laboratory in Ann Arbor, Michigan, and by vehicle manufacturers who submit their own test data to EPA."

Quite trustworthy to submit your own data, right?

Further searching reveals ...

"The city test is approximately 11 miles long and is a stop and go trip with an average speed of about 20 miles per hour (mph). The trip lasts 31 minutes and has 23 stops. About 18 percent of the time is spent idling (as in waiting for traffic lights). A short freeway driving segment is included in the test. The engine is initially started after being parked overnight."

"The highway is a 10 mile trip with an average speed of 48 mph. The vehicle is started "hot" and there is very little idling and no stops."

While I can't say too much fault with the city driving (beyond the fact that it's still tested in a lab versus reality), the highway speed is simply laughable.

Cars designed for the US will be optimized for these specs only, whereas "world" cars have other fuel economy tests to abide to - typically one that better suits the typical real-world driving speeds.

-- Kane

--
Blossom II - '91 745Ti/M46 ... Bubbles - '74 144GL/BW35 ... Buttercup - '86 245GL/AW70 ... The Wayback Machine - '64 P220/M40

The discrepancy you describe could be due to driving style alone, EPA figures are at the least obtained by somone bent on max economy. I doubt it could be proved a lie. But look at Chevrolet's Economy figures...The 1993 up Camaro, thanks to CAGS(Computer Aided Gear Selection where you shift first to fourth except on hard throttle) and 2 overdrive gears sport 30+ MPG with a manual trans. Rated better than most midsize economy cars, and better than any 4cyl sportscar!

I have read that the EPA mileage figures are generated in a lab instead of on the road. I think that their test cycle is intended to show emission characteristics more than true mileage.

There was a good snippet about economy testing years ago in the US. Cars with 5000 miles on them were run around a road trip in a convoy so that they results were "accurate"

Shutting engines off going down hills, racing up hills, and high tire pressures were the norm.

During the 5000 mile "break-in" tires were run underinflated to scrub their edges off for less rolling resistance (these were bias ply tires). Cars were run in the desert, without air cleaners, behind another car that drove on the shoulder to raise dust - this broke the engine in much faster!

Mark Twain said "Figures don't lie, but liars do figure."
--
96 855R, 95 855,854, 90 744 Ti - 343,000 Volvo miles put on 7 bricks

The milage figures come from BASE models, probably don't have AC, and are run on a platform with rollers to simulate resistance. If the motor and tran are different in the same model, an additional test is done with them. Yes the companies "cheat", but not by that much.
Most of your rentals have poor maintenence records and poor break in periods and guys with lead feet. No air pressure in the tires helps too.

Klaus
--
95 854T, 88 780, 88 245

I don't think this is still the case,but 20 some odd years ago when I went to mechanics school,one of my instructors , who was a semi retired former bigwig with the society of automotive engineers ( you know, that SAE you see on everything 'merican) told us that the method used at the time to come up with milage figures had a major loophole in it. They would run vehicles continuously around a banked oval track at highway speed for the hwy estimate and continuously at 35mph for city estimate.
But here's the loophole, there was nothing in the regulation stipulating what kind of tires or inflation pressure could be run, so they generally used a specially designed tire for this that had a single tread approx 1/4 " wide and they were filled with 200psi nitrogen, so there was in essence, no rolling resistance to account for, hence the high milage figures . I'm sure the current method has changed, but along the same lines.

It may sound like a tall tale, but this guy kept a $100 bill on his desk for anybody who could prove him wrong...never happened.( and $100 then would be like about $5-700 now, We ALL tried :-)

--
-------Robert, '93 940t, '90 240 wagon, '84 240 diesel (she's sick) , '80 245 diesel, '82 Mercedes 300SD

From what I understand, the U.S. governmet calculates fuel economy by a mathdmatical equation. As a result, mpg is inflated.

I heard a story on NPR about this recently. There are groups trying to get mpg estimates more accurately by actualy driving the cars around!
-pu
--
((1993 245 Classic, 94K)) ((1992 244, 106K)) ((1987 245, 271K - RIP)) San Diego