Gas mileage.

[nequamminor]

I have been getting my car around for the winter and such. I just recently tried to check my gas mileage and if I can divide then I've got some serious work to do. I drove my car 15 miles according to my trip odometer. BTW, the trip odo seems to rack up miles too fast, along with the regular odometer. Anyways, assuming its right, I had 15 miles on my full tank of gas. I went to fill it up again expecting a gallon of gas at the very worst. I had a gallon and a half in it when it clicked. I get less then 10 mpg. I don't have a cat, and the car has 194000 on it, but that still seems way extreme for being really really nice to it. All the driving was in town, but keeping it under 2.5 because the exhaust is loud. Any thoughts or ideas as to why my mpg would be so horrible?

[OldSkoolGP]

You might want to throw your system out and try running through a whole tank. A W-body has a 16.4 gallon tank. So drive it empty, but just record what your odometer says at full and empty, take that number and divide it by how many gallons it takes to fill it back up. That would be more accurate than topping off a mostly full tank. If you go 320 miles and use 16 gallons, that's about 20 MPG, so use that as a reference.

[z34phoenix]

yeah when i get gas i always top off... and reset the trip, so i know how many miles and how much gas....

with such a short sample as 15miles its very hard to get a good reading on mpg. also when you first put gas in, the computer will be making adjustments to the Air fuel ratio cause the fresh gas burns diff then the older gas in your car.

[DEI37]

Yeah, 15 miles is nowhere NEAR enough mileage to get a reading of off. If you went 150, that would be better.

[DEI37]

A W-body has a 16.4 gallon tank.

My 1992 Olds CS had a 14.7 gallon tank, and my '97 CS has a 17.1 gallon tank.

[nequamminor]

I had 140 miles on the tank and retried it. Filled up after 7.5 gallons. That gives me about 19 mpg. That was probably 30-50% city driving. Much better then the 8 I thought I had before. However I found out my AC compressor clutch is on the way out, just like on my old Grand Prix. I also found out the 3rd from the left vent setting is a/c too, and i had that on a lot... I think that has to do with my 8 mpg before... Other then that, I feel much better. Just thought I would let everyone know they were right and thanks a lot for the help.

[85_Olds_Ciera]

I went to fill it up again expecting a gallon of gas at the very worst. I had a gallon and a half in it when it clicked.

Uh...try several tankfuls, before you reach a decision.


There are people who do your method and tell me they are getting 40 mpg on "full sized" V8 motors...