Mark Miller Toyota Downtown

Toyota already has a best-selling line of hybrid vehicles in the Toyota Prius, but it still isn't satisfied. It seems there is more work to be done and more vehicles to be produced for the company to be happy about its fuel-efficient offerings. That's why the automaker launched its 2013 NS4 Concept at the recent 2012 Detroit Auto Show.

Toyota is making its way to be the top seller of hybrid vehicles throughout the world. They've sold over a million Prius sedans since the 1990's.

The Japanese auto maker also has a plan to sell one million hybrid vehicles (Prius, Camry, Highlander, etc.) a year.

Toyota has now announced their plans to introduce six new hybrid vehicles by 2012. The company has yet to revealed much in the way of details, apart…