fuel mileage question

[Mind_Boggler]

OK, I have been borrowing my sister's car, an '88 Plymouth Reliant, and the fuel economy is........ well..... wierd. lol basically, if I drive between 200 and 220 miles according to the trip odometer, I can fill up and it takes 6 or 7 gallons(it's a 14gal. tank) making approx. 30mpg, but if I wait until it's around 250 miles, it'll take 12 or 13 gallons!! :shock: What's the deal here?? how does driving an extra 20 or 30 miles make it use twice the fuel!? no one seems to know..............

[Glass]

Just buy a Ford and start driving it. Its the way the worlds telling you to drive something the mileage is consistant in, even if its a consistant 10 MPG..lol
I dont know..warm up time? City vs. Highway? Extra idle time? I really have no clue.

--John

[mattadams]

Sounds to me like one of two things, its got a goofy odometer, or the fuel tank is weird, or the weight of the gas makes a differece int he fuel mileage of the vehicle, LOL.

[Tray]

Something is definitely wrong in that equation.

There doesn't really seem to be any way to make that even happen. Any mechanical problems would affect it the opposite way.

Who knows, maybe you used different gas? Different traffic patterns? Someone siphoned your gas?

[Mind_Boggler]

nah, I almost always fill up at the same station, and the odo works fine........ I just think it's possessed.