| 08 August 2010

X-Tracer and ZAP compete for the X Prize. Photos courtesy of Progressive Automotive X Prize After a series of eliminations at Michigan International Speedway over the past several weeks, the original 136 vehicles that qualified to enter the Automotive X Prize were narrowed down to nine final survivors. In this 'revolution through competition,' the vehicles aimed for the best super-fuel efficiency -- 100 mpg o... Read the full story on TreeHugger