I tell my parents I'm going out with friends and then just drive around for a few hours
Any reason you drive around for so long?
Be the free spirit of the night.
That sounds empowering!  I think it's fine that you want to have some "me time", although you shouldn't lie to your parents in order to get it.  Try being honest about it and seeing what they say!
My parents... Some things never change.
Eventually you  will have to tell your parents what you've been doing. If you tell them upfront, I am sure they will understand. Even still, what you do with your own time is up to you and not their business.