Plug-in hybrids are still a big deal in the automotive industry and they seem to be forming the next big wave of green car technology. Several well-known automakers have joined the move towards utilizing the technology, with the lead taken by France's PSA Peugeot Citroen and its Peugeot 3008 Hybrid4. Audi is venturing into green technology with an A5 prototype that's the e-tron division for development of EVs.

Under the shell of the new A5 e-tron Quattro is a 211-horsepower 2.0-liter TFSI turbocharged gasoline engine mated to a compact electric motor. The electric component garners some 45-horsepower, but there's another electric motor in the rear that will make 81-horsepower. The prototype can also be plugged into a regular power outlet to charge the lithium-ion battery pack. On a fully charged pack, the electric only driving range is 40 miles. For now, this is only a prototype and any production release is still years away.