Quote:
Originally Posted by e39_touring
The trip computer is VERY accurate. Afterall, your ecu knows EXACTLY how much fuel it is injecting into the engine at any given time and how many miles since reset. By the trip computer, I could never do better than just shy of 21 mpg on highway trips, and now I'm getting just shy of 24 mpg on the same routes.
Intake and exhaust mods can very well change the efficiency. Ever hear of pumping losses? Think maintaining 600 deg temperatures in a catalytic converter is done without expending any energy? You often hear that an inefficient exhaust system only costs 2 or 3 hp or such and such, but when the vehicle only requires 20 to 30 hp to maintain it's speed on level ground, there's your 10%.
|
I disagree. The trip computer is not accurate in my experience. I log all of my fuel ups and track my mileage. My OBD consistently over reports mileage by .4 miles per gallon. The ECU does know exactly how much fuel it's putting in the engine, but I don't think that is how the OBD calculates MPG. In fact, my scanner has a function that allows you to adjust the reporting accuracy of the OBD. Unfortunately, it only works in liters not gallons. I haven't been able to figure out how to make the adjustment correctly. The adjustments I tried only made it worse, so I went back to "neutral".