The XMODS Evolution models were released in the autumn of 2005. They had substantial construction differences from the previous model and are available with either a car or truck chassis. The electronics were vastly improved, with one main board compared to two separate pieces in the generation 1 version. The motor was mounted transversely in contrast to generation 1's longitudinal layout. While the generation 1 chassis had a separate battery housing (each holding two AAA batteries) on each side, the Evolution chassis had one battery housing (holding four AAA batteries) at the bottom. This series was discontinued in the U.S. by RadioShack in mid-2007.