Hybrids don't belong in *multi-passenger* lanes. Should an Escape Hybrid that only gets 25 mpg be allowed, while someone with a 40 mpg Civic or Jetta is forbidden?

No.

The purpose of HOV lanes is to increase mpgs (25 mpg car * 3 people = 75 mpg), but MAINLY to *reduce the number of vehicles* on the road and alleviate stop-n-go traffic. Hybrids don't reduce the traffic load.