Mark D Moore of NASA had a presentation at the Electric aircraft conference and described a hybrid plane that could achieve 720 mile range and 100mpg with a speed of 80 knots (92.2 mph)
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.
The electric sailplanes and motorized gliders were discussed on this site as 438 mpg equivalent super-commuter planes with 100 mile 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 Pipestrel Electro will soon have a better continuous operation electric engine.
Lightweight gas engines are listed 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.
There are many experimental electric plane designs
All electric planes will get better range with expected improved technology
The small engines suitable for these light planes are also ideal for powering the DARPA exoskeleton, which would make real life iron men. Strength is boosted ten times.
CNET had coverage of the Pipestrel electro airplane
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.