Normally, if I'm not hypermiling, I'd never be accelerating from 30 mph in 5th gear, anyway. It would be 2nd or 3rd with as much throttle as I felt like and then drop into 5th when I reach cruising altitude.

Typical hypermiling, I'm dropping into 5th at about 35 and feathering the throttle to accelerate up to the speed limit using as little fuel as possible.

For THIS experiment, I've been playing with getting into 5th even earlier (30 mph) and giving the car more throttle. No, not full-throttle (not because I think it would hurt the car, but because it would go open-loop and run rich), but somewhere between half and 3/4.