AFS Trinity Power Corporation showed off its plug-in hybrid SUV, the XH-150, at the 2008 Detroit Auto Show. The car's power train represents a refinement of the hybrid concept by employing ultra-capacitors for fast acceleration under electric power. Traditional hybrids use batteries to power low speed driving, but kick in a gas engine when high speeds or heavy acceleration is required. AFS Trinity builds on this concept by adding ultracapacitors, which, unlike batteries, are designed to quickly discharge electricity, providing power to the hybrid's motors for fast acceleration. The company's demonstration vehicle, the XH-150, also features plug-in technology, letting its battery pack get charged from the electricity grid. Plug-in hybrids, without AFS Trinity's ultracapacitors, are reputed to get 100 mpg. The company tested the XH-150 at Michelin's Laurens Proving Grounds in South Carolina, and claims impressive performance, such as 150 mpg using the EPA Combined Urban/Highway Driving Cycle, a range of 40 miles under electric power, and full range of 400 miles using both electricity and gasoline. Using both gas and electricity, the car's 0 to 60 mph time was clocked at 6.9 seconds, while under electric power it took 11.5 seconds. Its top speed is 87 mph. The company is showing off the XH-150 with the intention of licensing its ultracapacitor technology to automakers.