Does anyone know the particulars on how the computer calculates the mileage? I've gotten so used to using it, I haven't done the fill-it-up and calculate it yourself method in a long while. Last time I did, I think the manual calculation was more than the car-computer. Questions:
What is the averaging algorithm? IE how long/far does it take to go from inner-city stop-go measurement to an accurate highway-long distance measurement?
What if you sit at idle for 10 mins, or an hour? Does computer reduce calculated mpg? It knows your speed is zero, does it count that in? (my manual claculation certainly does).
By the way, the computer-mpg on my na-S60 has gone down from 28.5 to 27.4, in concert with my daily comute becoming much shorter. But I recently took a 140-mile trip and expected the mpg to go up to 29 or 30 highway. Didn't happen. I'm about to replace the spark plugs (it's time) and am wondering if that would get me back 1 or 2 mpg....
skeeter123
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