If Batman needed to upgrade to a new vehicle, I think the Lamborghini Sesto Elemento would be a top-runner. Just add a few superhero tweaks here and there, and you have a badass car capable of anything.
As of right now, however, the Lamborghini Sesto Elemento is impressive on a more realistic level. Made predominantly out of carbon fiber, it weighs only 2,202 pounds, which allows it to accelerate from 0 to 60 in 2.5 seconds. Incredibly sleek and sophisticated, I can't help but think of it as a rare, faceted black diamond.