I have noticed that the Trip Computer seems to read about 2 mpg above what the calculated average is when I fill the car up. I have not had a chance to see how close the speedo is. I also think when the fuel light comes on you can go farther than what the computer says, but I don't plan to verify it on purpose.

 

I don't know how accurate those are anyway, I test drove a few jags for my last job, not that they are perfect, but two different models showed about 2mpg better than actual all the time.

 

Mine trip computer is always below what I calculate. anywhere from 2 to 6 MPG so far.

 

I noticed that my MPG was consistenly low by about 2 mpg versus the trip computer. Then I bought gas at a different station, andmymileagewas pretty much bang on with the trip comp.Seems the gas pumps atmy usualstation were ripping me off.

As you might guess, my usual station is no longer my usual station.

You might want to change where your buying your fuel, and see if that makes a difference.

 

My fuel is coming from two different places primarily. I did an "idiot" check while cruising on the highway to compare the computer to the speedo using the average speed feature and it seemed to be right on with the speedo on cruise. I need to borrow a GPS and see if it is all correct.