The first question that popped into my head is, how old are you, and how old is she? If you guys are too young to drive, I'm not sure how you're going to force anything. Sneaking behind your parents back can crush any trust that they have in you. And that can take years to rebuild. I suggest you sit down, and tell your parents that you really like this girl, and would like their permission to see her on the up and up. How you handle this now can form of the rest of your teenage years. Do the right thing. And in your heart, you know what the right thing is.
You probably shouldn't even be thinking about this. If they won't allow you to see her, it is because they have a good reason. Far from this, you can sit them down and talk about it calmly; you can even have them send someone along with you at a discreet distance.
There is obviously some reason that your parents won't let you see this girl. We don't know the entire story. As a parent, trust me, you can't force your parents to let you do ANYTHING. Sneaking out won't help. It will only make it worse.