The Opel Flextreme is a diesel plug-in hybrid concept small family hatchback created by Opel in 2008. The Opel Flextreme shares the same GM E-Flex platform as the Chevrolet Volt (front engine, four door).
It is based on the same GM E-Flex series hybrid platform used in the Chevrolet Volt, but using a diesel rather than gasoline engine. It can travel on its lithium-ion battery before a small diesel engine starts charging the battery.
The Opel Flextreme is a small family car with a 5-door hatchback body styling with 5 seats.
In January 2008, a rebadged version of the concept was introduced at the North American International Auto Show as the Saturn Flextreme. The Opel Flextreme was expected to emit 40 grams of CO<sub>2</sub> per km or less (according to European test procedure ECE R101 for range extender vehicles). It was expected to reach approximately .