Hi Don,

I drive a lot of miles each week, and check the mileage frequently. I do about 80% highway at 79 mph, and 20% country roads and city with stop lights and stop signs. I got 22.5 mpg in the winter and now 23.5 mpg, which is accurate from my fuel usage and odometer. A new owner, I thought I should do better, but then I looked at the sticker - 19 city and 26 hwy for mine. I accelerate rather conservatively usually - if you look at your instantaneous mpg it goes WAY down during accerelating, FAR below what my VW VR6 gets during that period. I don't know if the computer *avg* mpg would be accurate if you do 100% city driving. My guess is that it would be over several hours of driving, but perhaps not over shorter intervals.

Don 1995 850T

Hello,

The trip computer that Volvo used in the 850 is said to be one of the most accurate of any manufacturer. The MPG calculation uses info from the ECM as to how much fuel is injected, rather than comparing the fuel gauge with distance traveled (which could throw the reading off if the gas gauge was out of whack). The fact that it is using data from the ECM makes it very accurate. My wife has a 1995 850 Turbo and her computer has always been very true (even when she lets the miles to empty run to zero, the car still keeps rolling:). Anyway, that's my take.

I hope this helps...

Joe S. - Volvo Master Technician

1988 760 Turbo w/274k miles, 1981 242 Turbo w/243k miles

Just remember to reset the miles traveled before road trips to get accurate readings.

Klaus
--
98 V70Rawd(108Kmi), 95 854T(88K mi), 75 164E(173K mi)

I checked mine versus the computer a lot during the first year and it seems pretty accurate. I found it is more accurate when you go a steadier speed and less accurate with lots of acceleration and stopping. That makes sense because the computer is working with an average speed and distance stats along with the fuel usage (without accounting for evaporation or any other loss of fuel).

Mine was always within about 1 mpg or so. It's valuable for monitoring your general engine condition - you notice a sudden drop in mpg without changing driving patterns and you can investigate a possible problem.

Also I found it most accurate on road trips, when you need it the most!

i think you answered the question yourself the only way to guage accuracy would be to compare with how you figure manually against what the computer says.