Re-Thinking The Thousand Dollar Challenge Our thinking seems to be too narrow in the individual, vrs. mass transit, arena. Combining different types of engines, ie the hybrids, and different types of energy generators in one vehicle may make the most sense. One can include both wind turbines and solar cells in a vehicle to charge the batteries on the fly, and use either propane, natural, or methane gas to fuel the ICE. One ends up with a very clean, FE vehicle.