My last few fillups had the actual MPG higher than the computer's MPG. It was within about 1% though. Again I used a lot of data samples to average out the AFE Bias value.
* 2017 Fusion Sport, 12.7 @ 108 mph tune-only (early tune of mine, bad trans settings), full trunk w/ lunch, and dirty paper air filter
* 2014 SHO non-PP, 12.4 @ 111 mph tune-only, all day long with dirty paper air filter and worn out 30k RS-As