Green cars were on display at the Geneva Auto Show last week, fueled by rising oil prices and environmental concerns.

Car makers presented an array of cars that run on a variety of sources, from electricity to diesel. The Saab 9-X BioHybrid, for instance, won recognition for Best Concept for its 1.4-liter BioPower turbo engine backed by GM’s next generation hybrid system. Daimler showed a Mercedes SUV, the BlueTEC Hybrid. Nissan said it would launch an electric car in the U.S. in 2010, and release it worldwide in 2012.

General Motors confirmed its $4 million investment in Think Global, a Norwegian electric car maker, which debuted its Think Ox at the show, a five-seat car with a range of 125 miles per charge.

Daimler said it has a hydrogen model that can reproduced affordably in large quantities, but the lack of infrastructure presents a barrier. For others, biofuels, such as ethanol, are the name of the game. For instance, Lotus displayed a version of its Exige 270E Tri-fuel that runs on gasoline, ethanol and methanol.

Toyota, maker of the wildly successful Prius, also debuted its iQ model, which it bills as the world’s smallest four-seater.