A plug-in, flex-fuel hybrid car.
It has a 40-mile range on batteries and then falls back to a three cylinder engine that can be configured for gas, ethanol or biodiesel (giving a blended 50 MPG equivalent).
It has 110V plugs on both sides, but the cords seem way too short. I thought they should be extension cords, with spring-loaded retraction, so you can mooch power from your friends when you visit. =)
Concept cars seem like a tease to me since so few make it to production. (2009 update: this one looks like it is still going. fingers crossed)