Not one to be left out of the green movement, Volvo is working on a micro-hybrid that features start-stop technology for 2011, along with a true diesel hybrid for 2012, according to Motor Authority. That's in addition to Volvo's DRIVe line of concept cars, which the company debuted at this year's Paris Motor Show and are already slated for production.

The DRIVe concepts use a combination of lower-tech ideas like revised gear ratios, low-rolling-resistance tires, and improved aerodynamics. The new micro-hybrid, however, will feature the cutting-edge driveline technology listed above and also include brake energy regeneration.

"Of more technological interest, however, is the diesel-electric full hybrid slated for 2012," the report said. "Powered by either a D5 diesel engine or electric motors, or some combination of both, the car is expected to deliver up to 15 percent better fuel efficiency than a typical diesel," which could really be something, given how good regular diesel cars perform on this front. A plug-in electric hybrid is also in the works, but that one isn't as far along; Volvo hasn't set a target date for that model.