Hi, P.S. - - -
You can double check the computer quite easily and accurately. I've done it on both of our Volvo's (98 V70XC & 02 S60AWD). In both cases it may be luck, but the reported numbers are right on the money.
- Check the accuracy of the odometer. If you have any "official" measured miles on nearby Interstate Routes, use them. Those same routes have a mileage marker each and every mile, generally reporting miles from the western border on east-west routes, and from the southern border on north-south routes.
- This done, calculate mpg based on gas required to top off the tank from fillup to fillup, divided by miles covered during the interval. Compare results with what the trip computer is reporting. Since the required inputs are the same, verifying the one mpg range gives assurance that all functions are verified.
No rocket science here, just the numbers. On a recent trip from Reno to Elko, NV, we got exactly 31.0 mpg for the 300 miles trip. Fairly level road, all at about 5,000' across the High Desert. Average speed reported by the computer was just under 75, as that's the posted limit and I generally drive at five over. Most of us have gotten similar figures under similar inputs. There is one caveat, of course, and that's the "Miles to Empty" number, which changes as mpg numbers vary. This number is derived based on the average mpg over the preceding 12(?) miles (or is it 6?). You can drive around town for a few days after a fill up and see a number - then watch that number increase significantly as you hit the highway.
As to mileage vs cost of gas - once again we see that our fellow Americans have only one real concern: "Is it available?" Today's paper reports SUV sales for the past month are up by 18%(!!) from the previous month, while passenger car sales are down by a small %. For all the concern for these dubious economic times, it's clear that too many folks have altogether too much money - and no heart for conservation.
bob noble Reno, NV, USA