Mine tried the "I'm 18 and can do what I want" until I reminded him that he drives the car I paid for and is in my name. That I pay the insurance and gas. He eats the food I pay for and sleeps under the roof I pay for as well. That pretty much shut him up and he proceeded to take out the garbage!!!!
I like your style. It will be this way for mine also. When in high school they will have curfews, they will do what I tell them to do, and they have to get permission to do what ever it is they want to do. If they have a problem with it, then they can move out and pay their own bills.
All that being said, my kids aren't real social creatures. If they do go out and about, they really don't like to stay our late. I don't anticipate any problems with the rules when they turn 18 and are still in high school.