Depends on the car. If you go in trying to test drive a new corvette dressing all sharp and telling them you are going to put a 20k down payment on the car, even then they will only let you sit inside and rev it....unless you have your parents with you. The value of the car does make a difference. I found a way to get around this. Go to carmax. I was gonna drive a Porsche Carrera but I had already driven the M3 that same day.
Basically just tell them you are interested in the car and aren't set on a vehicle yet, you are still trying to decide but the car you wish to test drive is one of the ones on your list.