Their four competition vehicles were powered by small (250cc) one-cylinder
E85-gasohol-fueled internal combustion engines. The aim was to achieve the prize's requirement of 100
MPGe or higher
fuel economy. A small E85
internal combustion engine was chosen for the competition in order to have the lowest possible powerplant and fuel weight, high
energy density, low
pumping losses, and an engine design with an efficiency sweet spot at cruising speed; while meeting mileage and emission standards. The fuel-vs-batteries tradeoff was especially onerous in the mainstream class, because it had a higher 200-mile range requirement, doubling the potential size of a heavy battery pack for hybrid and EV designs. After Coast Down and before tests at Argonne Labs, Xprize officials determined: "The engine failures were found to have been caused by third-party drivers of the vehicles, however, and were not blamed on vehicle design or capabilities." Edison2 was permitted to provide independent third-party validation reports instead of undergoing the same validation testing as other finalist teams. Progressive Automotive Xprize posted Edison2's final MPGe results in a press release on their website. The tandem alternative class entry suffered catastrophic engine failure, possibly due to a software problem, and was also eliminated. == Current work ==