Hybrid aircraft; the rear engine is an electrically powered one.

Ampaire's Electric EEL technology demonstrator, a modified six-seat Cessna 337 Skymaster, keeps its Continental IO-360 piston engine in the rear and replaces the front piston engine with an electric motor in a parallel hybrid configuration. With batteries in the fuselage cargo pod, fuel consumption is reduced up to 40% over a standard Skymaster. The aircraft flew a 1,135-mile leg between Mojave, CA, and Hays, KS, a record for nonstop hybrid-electric aircraft enroute to this year's AirVenture at Oshkosh.