When I bought the car a month ago, the gas mileage readout said 17 mpg. I figured that was because it had been test driven a lot lately, and test drives are probably bad for gas mileage.

I was right, it steadily climbed as I drove the car. By the time I refilled the tank, it was reading 23MPG. Cool! Except by my calculations I only got 20MPG. Now, the second time I filled the tank, it reads 25.3MPG, and I actually still only got 20MPG.

What gives? Also, anything I should do to improve gas mileage besides keeping the tires to the correct pressure and a clean air filter? I'm going to check both of those after work tonight. Car has around 39,000 miles.

 

That trip computer is as innacurate as the tachometer.

Use real world measuring devices, i.e the pump readout and a calculator.

 

Biggest thing for immediate improvement in MPG is go easy on the pedal. And yea, that trip computer is always way too optomistic. Nothing is wrong with your car, it's normal.

 

Why is the TacoMeter not accurate?

 

As a Great Wizard once said "They're calibrated by third graders"

 

The tachs can be anywhere from 200 to 600 rpm too fast depending on whether you got the class clown or the valedictorian. The fuel computer in the car is hopelessly inaccurate because it only samples once every 30 seconds.

 

For teh win

 

Does anyone know how our computer actually calculates the mileage? I know in my old jetta, it used the injector pulses to calculate it. I didn't feel it was very accurate either.



James

 

To be honest with you I don't think it calculates anything at all with the way ours "works". Think of it more as an electronic lotto spinner that just randomly draws 1 of 5 pre-programmed numbers.

 

IIRC it is the injector pulses.....but sampled once every 30 sec. Almost as accurate as a blind man telling time by the sun.

 

mine also displays about 2 mpg higher than actual.

 

Mine is about 2 or 3 MPG optimistic. If your car is a manual you can cruise a very low RPM in city driving. The 3.5 doesn't seem to mind staying well below 2000 RPM as long as no strong acceleration is required. I've improved my milege that way. I could never get away with that in my old Hondas.

 

How come I don't have a gas gauge?

 

Didn't start until 02 models