FACT:
Nice cars attract chicks, let's not fool ourselves. For whatever reason, be it the "fun" factor, media hype (movies, etc), or the money factor, a nice car will definitely help your game.
That being said...
Unless your car is a royal piece of dog shyt, it will not kill your game. Personally, I see the car as a tool for getting from point A to B. Of course, what I do for a living requires extensive travel.
In my experience, the women who care the most about your car are the ones with the most gold-digger tendencies. Kind of ironic, because most anyone outside of inheritance who becomes wealthy doesn't do so by taking on the massive liability of having an expensive, tricked-out ride. It blows my mind just how many people I know who bust their hump to make the payments (and repairs, insurance, etc) on their car. You don't have to pay an arm and a leg for a car that's decent, you just have to look around. I don't know about you guys, but I'd far prefer to become successful with money in *reality* rather than with a fake image which hinders that reality from ever happening.
The bottom line:
Unless you have a massive amount of cash on your hands, your main passion in life is cars, or you have absolutely given up on the possibility of financial independence, get a car that's practical. If the chick digs you for you, it won't matter to her.