P51C

I always hand-calculate and I drive the same way, on the same routes, at the same times, mostly. So, on my regular urban routing with my normal driving behaviour, over many tankfuls, I saw this gain. I actually wasn't expecting a fuel economy gain of any kind but there it is and it's still there, in almost a year of testing.

I believe it's largely due to the torque increase from the advanced timing down low requiring alot less pedal in stop and go. My datalogs reveal the tune is AFR consistent with the stock tune so, any fuel changes are limited to some cell trimming. Timing is the main change, as far as I can tell.

WJBertrand

Just installed the Pro-Cal II tune this weekend. After about 14,000 miles I've averaged about 21 MPG in my typical driving. I'll be keeping an eye on it moving forward. If you have 50 MPG calculations before the tune and compare the average to 50 MPG after, just use a Students-T comparison of means from both groups to see if there's a statistically significant difference. There's a function for this within MS Excel. 50:50 comparison should be plenty of sample size.

spectreman

I considered the Pro-cal but went w/Steeda 87 & 91 tunes instead, as well as their CAI & GT500 cans. Those points aside, the engine in totally stock tune/exhaust/intake was returning a miserably low 16-17 in city, 21 on the highway. W/the bolt-ons, my mileage changed nary a whit to the negative in spite of the increased HP/torque, and even perhaps picked up a .5 mile per gallon on the highway but certainly nothing noticeable. To me, that was a partial win because even tho I get on it a bit more to hear the roar or feel the added power, it hasn't negatively affected mileage. YMMV.
Lee