Check out the Discovery show "Future Cars: Fuel" (some are being rerun on National Geographic Channel and Discovery Science Channel). They showed some fantastic possible future power systems.
Losi 8T 1.0, Savage Flux - XL style, LST XXL, Muggy, 3.3 E-Revo Conversion and sitting outside 425hp, 831 Tq Dodge Ram Turbo Diesel. It SMOKES