Volkswagen (VW) is no stranger to fuel efficiency in the United States. While the company may currently known for its 200HP GTI pocket rocket and Eos retractable hardtop-chick mobile, the company also has deep roots in diesel motors.

The company is famous for its TDI engines which in recent years have been available in a number of vehicles including the New Beetle, Jetta, Passat and Touareg. TDI engines are currently on hiatus in the United States due to more stringent emissions requirements, but VW will bring to market a new Tier 2 Bin 5 TDI engine for the Jetta next year (and likely also for the Passat, New Beetle and Rabbit).

If VW has its way, consumers may have an alternative method for achieving high fuel economy with its vehicles.

VW is looking to introduce two variants of its recently introduced Up! rear-engined concept car. The tiny Up! measures just 135.8 inches from nose to tail and is only 64.2 inches wide.

The first variant of the Up! would be a small minivan aimed at families who clearly don't need all of the space afforded in today's super-sized minivans from Chrysler, Honda and Toyota. The second variant on tap is a plug-in hybrid model.

The plug-in variant would ditch the concept Up!'s hatchback profile for a more traditional sedan configuration (which is more in tune with American buying tastes). According to Auto News and Autoblog, the plug-in hybrid Up! would achieve close to 100 MPG.

The Up! minivan is scheduled to be unveiled shortly in Tokyo while the Up! plug-in hybrid will bow in Los Angeles.