I know LOTS of quality women who are completely turned off by Porsches and Corvettes. They say the guy is DEFINITELY compensating for something, and they aren't talking about money.
You're WAY better off showing up in a decent four door that's clean inside, and taking her to a good restaurant and a show. Cars are really a guy thing. Oh, yeah, while you have her out, it's usually a pretty good idea to STFU about you, and let her do the talking. Most Porsche guys I have known were pretty into themselves and couldn't hold a conversation with any human being that wasn't centered around themselves, car styles (but not technology), or ball and stick sports. And OH, isn't my Porsche just soooo cooool. And don't I look soooo good in it. Yeah, women are impressed with Porsches. So impressed they walk the other way unless they are pure gold diggers.