It appears Torque over estimates the mpg's by a slight amount, at least on my car. Here's the last two days morning commutes showing engine temps and trip mpg's. Interesting to me to see how horrible fuel efficiency is on a cold engine and how directly related it is to engine temp.
Both these days had similar winds (very light) and road conditions with just the ambient temps being different.
With my current vehicle configuration and fuel filling place my vehicle trip mpg has averaged 2% optimistic from hand calculated fill ups for the last month. Torque seems to be ~5% optimistic from the vehicle trip mpg. So, the Torque data seems to skewing the mpg's about 7% optimistic.
2011 335d 11.8 sec 120 mph 1/4 mile NHRA certified track
2004 Ram Cummins with lots-o-mods