Do you trust the trip computer ?

[Vectrafan]

My fuel gauge said just under 1/4 of a tank left. My trip computer said 39 miles left so I filled up just to be safe. I could only get 40 litres of fuel into the 61 litre tank, so it would suggest the trip computer ain't that great at guestimating the remaining mileage.
When I flipped over to mpg, the figure was 29.4 (this was around town) so my maths would suggest that I had at least 20 litres/4 gallons @ 29 miles remaining..........Range should have been a healthy 116 miles.

I wonder if this can be re calibrated by vx ??

[VauxVeteran]

If you use it properly it's 95% accurate imo, but when ppl reset things on it with half a tank left it can throw it out, I reset mine for each new week, and when I get filled up at the end of it the fuel figure is no more than 2/10ths out.

[Caterman]

The fuel remaining on the computer will also be dependant on how you are driving at the time. If you have been doing some "spirited" driving when you are getting low it will obviously affect the range left.

[Vectrafan]

On my Vectra B, I'd always reset only after filling up, which is a habit I'll stay with on this one.

Re the 39 mile estimate, even if I was flooring it, I'd still say it was wildly inaccurate, as this would leave me a return of only 10mpg for the last 1/4 of a tank instead of approx 22mpg ??

On the flip side, now that I've refilled, the range is suggesting 241. This is a bogus figure because there has not been enough miles covered for the system to recallibrate itself. A lengthy run up the M3/M25 tomorrow should see that figure move upto 350 ish plus.

The car goes back to the dealer tomorrow to have the passenger window switch replaced under warranty so I'll mention it just to put my own mind at rest.

[david173]

It would only work the best if you drove the same way all the time, sometimes mines is down to 30 miles say, and I'll drive to work on the motorway witth the cruise on at a nice little 50mph and watch it creep back up to 40 odd. I read somewhere it uses the data from your last 20 miles of driving or thereabouts. Therefore its really saying you have X number of miles left, if you keep driving the way you have done for the last few miles.

Last week i did have it down to 0miles and filled up about 5mins later, got 55 litres in the tank leaving 6 litres at least, well over a gallon, hence at least another 25/30 miles. We all chance it sometimes tho and run it down to the red, its just trying to be safe, otherwise we'd all be on the hard shoulder! I think they know even when its flashing empty we all expect there to be something in the tank even then!