You don't make these decisions in one go. One ad doesn't make someone who isn't into cars go out and buy a BMW. The money is in tipping someone who's been thinking about getting a BMW for a while over the edge.
I wasn't talking about people who aren't into cars at all. I was talking about people who aren't into BMWs in particular. If I'm about to spend a lot of money on a car, I'd think that BMW would want me to know about theirs.