car mileage

[MikieFinn]

I read on this forum and also in some fishing magazine tip on conservig gas.

Now from people say your gas consumtion goes up something like 1% for every 1 mph over 60.

How was this tested - under what kind of conditions and what vehicle?

I made the test myself. I have rather long commute to work so if I could save some gas it woulfd be great. I have always maintained areoud 70 mph. Since my little car is down I was driving my fishmobile to work for a while. It is 1999 Dodge Grand Caravan. Driving for few weeks the computer shows average milega to be 22.9 mpg. Ok so I think to myself let's see if I can save some cash here. I reset the computer and drive for two weeks the same way ,under same conditions for two week. At the end of that period computer shows 21.8 mpg average. So I actually burned more gas!! I go back to my wicked ways of driving around 70 after resetting the computer once more. After two weeks it shows - you guessed it 22.9 mpg.

I would like to know where does this information come from EPA?

Is my car wacky?


Than on the side note. My regular long distance voyager - 2000 Dodge neon is rated at 32/27 mpg. I get 33 average!!!!

My son in law has a RAM rated at 17/13 he never gets more than 15.

I do not think I will ever again belive anything about milegae unless I test it myself.

Wait if driving my fishmobile faster uses less gas than maybe I should drive around 100?

On the other hand that would put a dent on my budged in the form of the traffic tickets.

Local law enforcement "likes" speeding cars very much. They stop them all of the time I think they want to chit chat.

[TyroneFly]

I have similar results with my Acura TL type S. My car's mpg improves by nearly 3.5 mpg when driving 80 mph versus 65 mph. That's nearly 50 miles extra per tank full. Unfortunately, at 80 mph the fines of a speeding tickets and increased insurance premium exceeds the benefits of the mpg gained.

[Betty Hiner]

Tripped to South Dakota and back in the past few weeks (just got home Wednesday). Set the speed with the cruise control to 3 miles above the posted speed limit ( oh! daring me!!). Let the car do its' own thing, and averaged 32.2mpg. It's a 07 Honda CRV said to get about 28mpg. Good bit of that time, through Nebraska, Iowa, Missouri, and Kansas, we had the AC running. Think I did pretty good!

[Bobinmich]

Mickie

To explain it all would take some time. Quickly, steady state fuel economy is influenced by the rolling resistance of the vehicle, the wind resistance of the vehicle (aerodynamics), and the brake specific fuel consumption of the powertrain. All vehicles get better fuel economy as speed increases to some point determined by the aforementioned. Then the fuel economy will get worse when speed is increased further as aerodynamic losses start to dominate. The speed at which this reversal happens varies with the type of vehicle, engine size, axle ratio, aerodynamics, tire size and type, and more. It can even vary somewhat between seemingly identical vehicles. It is usually between 50 and 70 MPH. EPA numbers are obtained on a chassis dynamometer with simulated generic wheel loads to approximate actual conditions. They are only accurate at the tested points and conditions and actual results can vary widely.

Bobinmich

[analogbob]

Well, that explains why an '84 Chrysler 4 cylinder my wife owned didn't start running good until it hit 68mph.

Never could keep hubcaps on that thing either. Hit a small pothole and they turned into frisbees!
Bob

[Betty Hiner]

Could also explain why I got better milage going down hill with a tail wind!!!

[MikieFinn]

So it looks like the sticker put on the car by the manufacturer is just another marketing gimmick. Why I am not surprised? Silly me. I always thought that there was some sort of regulation cotrolling these people's honesty. HA!!!! Joke is on me this time.

[MontanaMoose]

Yeah and not only that, what about the in-dash avg. mileage readout? Could I possibly be getting 99 (never goes over that) mpg? Sometimes if I reset it just as I'm starting back from up on the North Umpqua (mostly downhill for 50 miles) I'll show 49.9 mpg. How is this be possible in my Malibu Maxx with 3.5 litre V-6 and 200 HP?

Cheers,

MontanaMoose

[Bobinmich]

Mickie

Sticker fuel economy numbers are obtained by running many data cars on a durability course for 100,000 miles and testing them every 5000 on a standard EPA test cycle in an EPA certified lab. It is very expensive and nearly impossible for a manufacturer to "cheat" on them. The reason they vary to actual usage is that fuel economy is dependant on how and where you drive and is different for almost everyone. The test is used by the Federal Government in determing compliance with the Federal fuel economy laws. It is also very good to compare car lines or say a SUV against a compact.

A primarily down hill cycle - such as driving down out of the mountains does result in a very high fuel economy average for that particular event. If you pumped your tires up rock hard and drove downhill from Loveland pass to Denver (or similar) you milage could approach the maximum on your milage meter (99 on some cars). Reverse the trip on low tires you could be in single digits. The longer you go between resetting you digital milage gage in your car - the more accurate the reading will be.

Bobinmich

[crazy4oldcars]

I just saw a news story a few weeks ago about the window sticker mileage. It seems that the test to determine the sticker numbers is over 30 years old. The original test criteria was based on a survey of driving styles at that time. Since driving styles have changed somewhat in the intervening time, the tests now yeild higher results than what most people experience.
The report stated that "they" ( I don't remember which agency) were trying to have the criteria revisited, and force the stickers to show lower, more realistic numbers.

With the disclaimers that the dealers always put on the end of the car ads (YMMV), I never put much faith in what was on the stickers, anyway. All they were good for was to make a comparison.

Kirk

Edit: I found the story.

http://www.usatoday.com/money/autos/...ids-usat_x.htm