Big part of matching the 1320/mph=et formula is clutch/converter/gearing that allows the engine to operate between it's torque peak and it's horsepower peak. When you have that, it's usually pretty easy to come within a few tenths of the formula. It's those last couple of tenths that require quite a bit more effort.
The formula is a general yardstick for comparing efficiency, it doesn't care much about power/weight ratio or how expensive your engine is.
I believe a lot of the discussion here is a difference between a low-powered high gear automatic mid 13 car getting traction as opposed to a high geared clutch car mid 11 mid 12 or worse yet 10.99 or lower getting efficient and traction??
Do you believe this fine line gets even finer?... As in shedding 100 lb getting you that extra 10th at certain levels..
