Wayne is probably going to be the definite answer here -- but I guess neutral is better. Pumping losses at very low speed is going to be substantial, even on *only* 3 cylinders.

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."