Define 'hard' acceleration. To the marathon men, it meant an instantaneous MPG of 20 - 30 at 30 miles per hour. Most people would call that gentle to moderate.

The OP's equations do not take into account varying engine efficiencies at different power demands.

R2-E2, 2G Prius.
Highway/City/Husband/Wife MPG: 56.5, as of 12/2005, 26K miles

Jac Nasser, Ford President: "We are planning to launch a hybrid version of
this car [P2000] within this year [1998]. We will also make FCEV available in
2004."