The Ford C-Max Hybrid replaced the Escape's hybrid model. This process is called regenerative braking on hybrid and electric cars. The savings are questionable relative to hybrid or diesel cars. General Motors has been testing the Opel Astra Diesel Hybrid. The rare, second generation hybrid was called a litigon. The Leaf is generally cheaper to operate than gasoline and hybrid cars. Also new is a S400 Hybrid version. Gujarat also leads in upcoming hybrid and electric vehicle manufacturing facilities. Its price was lower than the Civic Hybrid and the Toyota Prius. GTE are plug-in hybrid electric vehicles. Trunk space is improved both for the hybrid and standard models. It is capable of asymmetric warfare with conventional, irregular, and hybrid forces. Gasoline, hybrid and natural gas variants will be offered. Collaborative filtering is still used as part of hybrid systems. This is only true for specific hybrid systems.