Excellent -thanks for putting me in, Mike.
I like the plan to fill to the brim for MPG measurement. Are there any vehicles registered that *can't* be filled to the brim? (CEL / evap issues?)
If so, after this year's Green Grand Prix, for those vehicles I'd recommend some sort of simple dipstick measurement to fill at least to the same point, part way up the filler neck, rather than "1st click". 1st click is faith-based filling
; a dipstick is primitive, but it's scientific. And I believe the EVAP intake is usually right at the top of the neck, so it would still be OK to do.