mpg computation

[Andrei Kogan <abk@phy.duke.edu>]

Hello,
The trip computer in our 90q *sometimes* incorrectly displays both the
instantaneous and avg mpg. We usually get about 31 mpg on highway and that
is vconsistent with the what I see at the pump. Sometimes, it reads much
higher, something like 50 in the city/ 60 on the highway. This is after
resetting when driving steadily at 75-80 mph, so it has nothing to do with
peculiarities of coasting, for example. Both elapsed time and avg speed are
correct.  The instantaneous values are consistent with averages.

Question --- where does the computer take the signal for the fuel
consumption rate from?


Andrei