LiqrSicc

So how is the MPG actually calculated? What are the factors that affect the calculations? RPM and how hard you step on the pedal? Just curious because I'm wondering how acurate the reading really is.

Fern

Next time you fill up the gas tank monitor the amount of fuel you put in.

Drive the car as you normally would then on fill up again, note how much fuel (quantity) you used up and what distance you travelled.

Do this over a period of 3 times in mixed (city and hwy) traffic and you will in essence have calculated the most accurat mpg consumption.

You will find the onboard reading is not as far off as you suspected... At least in my case it wasn't

Cheers,
Fern

HarrierAWD

FWIW: I find the on-board computer consistently over-estimate the gas mileage by about 0.5 MPG, based on my own calculation.

salimshah

The issue is "how does the computer calculate mpg?". Distance by wheel roations (+/- based on tire wear), but how is the volume of gasoline measured.

Is it fair to assume certain volume of gas per engine rpm? In a carb based engine one could not, but in fi maybe?

Salim