Vroom
Vroom is a racing and vehicular-zombie-flattening game for iThings, Windows and (any day now) Mac, based on Shotgun Sunrise and made with the UDK (Unreal Development Kit). Drive your big blue truck around three zombie-infested tracks, boosting up half-pipes, catching mad air, and revelling in your extermination of the loathsome undead.
You can see videos of gameplay HERE and HERE (both were copied from an iPad rather than a PC.
You can also see a video of the PC version from the developers site HERE
Download:
You can download the game from Desura HERE (you will need the Desura client for this game, but it's well worth having for the number of free games many of which are top notch games (over 90 free game snow and rising every month).
The developers site can be found HERE, with a link to a download page HERE, but I wasn't able to access the non Desura download.