Why you actual mileage DOES vary!

[diamondtim]

Hi All,

Saw a news report (or internet report, can't recall) on why we often don't get the same mpg out of our vehicles that the window sticker states.

Apparently, the auto companies and EPA worked out a test where the car tested is put on rollers in a room and run in a start and stop mode (city) and a continuous run mode (hwy) to determine the mileage that that car gets for the sticker. This is done in a testing room with no wind resistance or temperture differentiation and the speed never exceeds 60 mph.

One of the consumer magazines ran the same cars on a test track outside and found that the mileage they got was lower by as much as 30-50%.

Maybe this is not news to some of you but it was a stunner to me (sheltered life, I guess).

I guess when the debate for higher mileage ensues (and it will). Maybe we can demand realistic testing at the same time.

[auntieemu]

I knew it was a labratory controlled experiment, no wind resistance and on rollers - but for city driving it is stop and go (18 or 20 times I think) and there are two tests that they average - one from a cold start like from the car being left over night and one from a hot start after it has been running a while. Then they lower the figures by a percentage to account for error. The highway driving is nonstop and is also lower a percentage to account for error.

For me, I've always found that my mileage was pretty close to what they said. For my sister (who tends to drive faster, slam on brakes and so forth) it is less. I swear, she is rough on a car - loaned her my little chevy once and after two weeks it needed another front end alignment plus a tune up. I had just had new tires put on too.

[clovis]

I think alot depends on how you drive the car, in many cases. Some cars never seem to get any better than the window sticker. Sometimes, though, cars will get better mileage than what the EPA states.

I got blasted once before for stating this, but it is true:

Our new Chevy HHR with the base engine, automatic transmission, gets much better than the window sticker of 35 MPG on the highway. I do drive very conservatively, watching my stops, driving ahead for red lights, and having slow take-offs, etc. Last week, driving 60 MPH on mostly a state road, but did include some in town driving, we got 42 MPG. This is pretty normal for this car.

If you drive the car hard, mileage will fall.

The Chevy HHR is a gas miser....it just sips the stuff. I am sure I will get blasted again or called a liar, just because the car doesn't have a foriegn name plate.

I am thankful for this car with gas at nearly $3 a gallon. If you are in the car market, I would strongly recommend you take a look at the HHR.
clove

[btai]

I try to draft behind larger vehicles on the highway as much as possible, especially in my old 1991 F150. You can tell a big difference in how much you gotta push the pedal down and in lower RPMs...I figure it saves me a few mpg

[rambler]

Clovis - I never heard of an HHR. What's it based on? Is it new or old platform? I don't think Chevy makes anything that isn't cloned on the other platforms; or cloned by a forign partner.

And - I don't doubt you, the EPA milage is one number, individual habits will affect real world numbers greatly.

--->Paul

[clovis]

Rambler-
The Chevy HHR is a new model that was introduced last fall. It is an all new design from Chevy, not an import clone of another model.
When we bought this car, finding an HHR was very hard, since demand greatly outpaced production. I have heard that this is still true. Our local dealership got 4 new HHRs in, and they were gone in less than a week.
HHR stands for Heritage High Roof, and is supposed to borrow its design lines from a '49 Chevy something or another.
We absolutely love our car, and the gas savings. Google HHR if you want to see a picture.
clove

[WisJim]

These tests were devised so that you could make a comparison between vehicles, not so you could find out exactly what mileage you would get. I find that I usually get better mileage than the sticker says, because I try to be careful not to accelerate too hard, or drive too fast. But I do keep up with traffic.

[Janon]

Yup, many vehicles have very inflated fuel efficiencies.

There are sites on the net that post "real world" fuel efficiencies - where they drive/use the car for thousands of miles just as you would - figures are shown for the various seasons - and they vary quite a bit.

cheers,

[dcross]

Heck, when they switch from winter to summer blend I get an extra 40 miles per 10 gal. tank.

[Oilpatch197]

Originally Posted by WisJim

These tests were devised so that you could make a comparison between vehicles, not so you could find out exactly what mileage you would get. I find that I usually get better mileage than the sticker says, because I try to be careful not to accelerate too hard, or drive too fast. But I do keep up with traffic.

No, it's social engineering from the goverment, they want you to "think" your saving gas by driving 55, but in reality it could vary and what better way to control the sheeple! Drive 55 or you die!

[HiouchiDump]

I've been told I drive like a grandmother. I usually drive at exactly the speed limit (less where it is 70) and I use cruise control on the freeway for any trip in excess of five miles. I always beat the EPA estimates by around 10-20%, depending on the car.

Driving style and environment are probably the biggest factors in mileage, after the car itself.

[SolarGary]

Originally Posted by diamondtim

Hi All,

Apparently, the auto companies and EPA worked out a test where the car tested is put on rollers in a room and run in a start and stop mode (city) and a continuous run mode (hwy) to determine the mileage that that car gets for the sticker. This is done in a testing room with no wind resistance or temperture differentiation and the speed never exceeds 60 mph.

Hi,
I believe that the current EPA tests do account for wind resistance -- you can simulate any wind or grade resistance you want with the roller (dynamometer) system.
http://www.fueleconomy.gov/feg/factors.shtml

They don't account for air conditioning use, and the city and highway tests are (apparently) not to realistic on speeds, accelerations, ...
The EPA is in the process of updating the test.
I still think the EPA ratings (even as they are) are helpful to compare cars -- it was much worse before they had the EPA ratings.

I have a Prius, and I keep very close track of the mileage -- on the highway I get the EPA estimate of 50 mpg (with a crusing speed just under 70 mph) -- around town I get 48mpg, which is less than the EPA of 65 mpg, and our town is not very big :-)

Gary