[dcb]

those are extremely large engines, not really applicable to personal transport. Nothing is impossible, but many are impractical. peak bsfc tends to go down with smaller engines, though reducing the power demands is usually more effective, unless you are talking about (serious) mass transportation.

And I agree, an electric motor usually benefits, efficiency wise, from having some gears to choose from, electric motors only attain peak efficiency under certain loads and rpms. The batteries themselves benefit from reduced current demands.