The plug-in technology demonstrator has the original 5.3-liter, 14-miles-per-gallon (17.l/100 km), V8 engine removed and replaced with a much smaller 2.2-liter turbocharged, four-cylinder EcoTech engine. As a series hybrid, there is no mechanical connection between the engine and the wheels – the EcoTech drives a 100-kilowatt generator only, which charges three lithium ion battery packs of 30 kWh battery capacity. This, says Raser, will give an electric mode of 40 miles. Although the engine capacity more than halved the addition of the battery packs, the electric motor and generator raises the curb weight by more than 20 percent to 5720 lb (2594 kg).
The standard Hummer four wheel drive, automatic transmission and transfer case is retained but moved back in the chassis to accommodate a 200kw AC induction motor, bolted on where the petrol engine normally connects. Mechanical losses through the 4WD transmission system are about 40 percent and the use of an automatic transmission mostly eliminates one of the main benefits of a hybrid, brake regeneration.
