The plane could fly from San Francisco, CA to Salt Lake City, Utah in less than 8 hours (using 8 gallons of gas) or from San Francisco to Los Angeles in less 4 hours (using 4 gallons of gas).
The proposal is to slightly modify a newly introduced electric sailplane by having several small electric engines for more safety and to add a compact combustion engine for more range.
Electric planes are flying now. The Pipestrel electric glider plane exists now. The lightweight gas engines exist now.
The Pipestrel Taurus Electro, motorized electric glider plane, flying in the air. More photos of the Pipestrel Electro are here
The engine for the Raytheon Killer Bee UAV only weighs 16 lbs and can get up to 25HP.
The Revetec X4V2 is 105 kg and gets up to 87HP.
RadMax rotary engine is 42 lbs and 40 HP.
Integrating working engines with working electric planes. Iterate designs and build to perfect but the engineering is very close to creating working prototypes. It will then be a matter of scaling up production.
The glider weighs little more than 700 pounds and costs $133,000.
Richard Jones, a technical fellow at Boeing Phantom Works. The research group is designing a plane-car hybrid to travel up to 300 miles at a time. Jones believes that by 2030, precision navigation systems could make it easier to pilot a compact plane than to drive a car.
Engineer Greg Stevenson displayed a two-cycle diesel engine that weighs 18 pounds and can run on biofuels.
The Speculist has a take on making the electric/hybrid flying planes convert into cars by having the wing section detach. The electric/hybrid car would be like the lightweight Aptera three wheel car.