Who owns the vehicle you're planning to drive on this trip, Brittany? Who pays the gas, insurance, maintanence, and taxes on it? In whose name is the vehicle registered? If you own the vehicle and maintain it yourself, and pay the insurance on it, then it really isn't your parents' concern what you do with it. IF, HOWEVER, your PARENTS are the ones who own the car and it's registered in one or both of their names, then they have every right to decide whether you can drive it or not, regardless of the length of time that you want to drive.
Why is it so important that you DRIVE to see your boyfriend? There are other ways to get where you want to go that are much faster and safer than driving. You can fly, go by train, or take a bus- and that's just for starters. There's more going on here than you're telling us, Brittany. And for your information, your parents are smart not to allow you to drive what is probably THEIR CAR for so many hours by yourself. Driving is extremely TIRING, Brittany, especially when you do it for hours at a time without interruptions or breaks. Safety experts who work for the government and various health agencies generally recommend that you stop every 2 hours or so on a long trip and take a 15 to 30 minute break, and that no one should drive more than about 8 hours a day, maximum. The purpose for taking frequent breaks, beyond the obvious physical benefits, is to allow your brain some down time. Driving requires constant alertness, and that in itself is very fatiguing to your mind.
If you must take such a long trip, you need to PLAN AHEAD and decide well in advance what your route will be, both going and coming home. You also need to get the car checked out by a mechanic to be sure it is roadworthy BEFORE YOU LEAVE HOME. Plan on taking a cooler with your lunch and plenty of NON ALCOHOLIC drinks- staying hydrated helps to prevent fatigue and what the experts call "highway hypnosis". And BE SMART, not sorry, and DON'T DRIVE without your parents' knowledge or permission. Do you even realize that your parents are within their rights to report the car as STOLEN if they come home and find you've taken off with it? You could easily get pulled over by the cops and arrested for theft, and car theft is a FELONY, Brittany. Instead of spending the weekend with your boyfriend, you could very well end up spending it in the slammer if you take off in your parents' car without asking them. You're not a little kid anymore- you're a grown woman now. So how about ACTING THE PART, and cutting out the sneaky behavior? Getting arrested and charged with grand theft auto is not the way to impress anybody, and I am sure I don't need to tell you that. If you are in college, the college administration won't look kindly on such behavior, and you could end up getting suspended or even expelled from school. I grew up in the midwest, near Purdue University in Indiana, and every year I was growing up, there were always a few kids who got kicked out of the university for pulling stunts like the one you're describing in your question. And it isn't just colleges which are less than impressed by such behavior- pulling a stunt like this and getting arrested for it could hurt your chances of getting a JOB once you get out of school- assuming you even manage to finish, that is. Employers don't like and aren't impressed by people who have criminal records, and they don't hire them. You need to ask yourself if taking off in your folks' car without telling them is really worth the potential price you could pay. If this were me, I'd be saying heck no, but you need to make up your own mind.
PS: Just as a matter of curiosity, how come you posted this question in the "Cats" section? It has nothing to do with cats.