Be a thin dude with a scraggly beard, a slightly dirty t-shirt that should have been replaced a year ago, clean "I don't care about fashion" shorts, no more than minor body odor, and perfectly fit glasses. Speak somewhat intelligently, but act a bit weird. Stare at random everyday objects occasionally, as though you are thinking deeply about them. In the right parts of the country, they'll let you test drive, no problem at all. They'll think you're a .com millionaire. The hair and the glasses make 90% of the impression. I may or may not have test driven Porsches and Maseratis like this.