Apparently its bad for vampires, and they don't know it, even buying an Audi with them.
If I remember the commercial correctly, I think that they didn't use the car headlights to light up the undead, as the lighting appeared to be more flood like, with no beam cut off. I would expect the car's headlight pattern to have a nice sharp cut off, but even at close range, their faces, while standing, where lit up brightly, they had to shield their eyes from the glare, etc.
So, I'm thinking that either the Audi headlights will NOT kill vampires, and they had to use perhaps a foursevens stopsign light or some other similar source...or, that they were in fact not really vampires.