Opel Flextreme Dynamic Versatile Flexiblehttp://www.policy4less.com Check out the amazing Opel Flextreme. The Opel Flextreme is a diesel plug-in hybrid concept car created by General Motors. Opel Flextreme is a plug-in hybrid that can travel 55 km on its lithium-ion battery before a small diesel engine starts charging the battery (it is a series hybrid). The Flextreme uses the same platform and technology as the Chevrolet Volt. However the Volt is designed for a North American market, and as such also includes a version that includes a gasoline engine with a sedan body.