How long do you have to go to school to be a professional NASCAR driver?

You don't. Professional NASCAR drivers aren't selected because of their educational background. They're selected based on their talent, knowledge, teamwork, and marketability. Education might play a role in helping to build knowledge (for example getting a mechanical engineering degree could theoretically help expand your knowledge of your vehicle's systems) or improve your teamwork skills (more opportunities to collaborate with others). But strictly speaking education isn't the key to becoming a NASCAR driver. What you really need is a lot of talent and a lot of practice. Pros often start at a young age with Karting at their local track, then move up in vehicle classes (referring to the type of vehicle not the types of classes you see in school) as they gain experience and make a name for themselves. So if you really are determined to do whatever it takes to be a professional driver I'd say you should start writing at your local track, save every penny to spend on racing, learn as much as you can about vehicle systems, get an internship or apprenticeship with a racing team, and start spending time doing teamwork building exercises like joining the scouts or spending tune volunteering at your local YMCA.

HOWEVER, does that bean you should drop out of school and start racing all day every day? I wouldn't recommend it. Here's why: becoming a pro NASCAR driver is a highly risky ambition. Many try. Few will succeed. Just like other entertainment and talent fields like football, singing, ballet, rapping, or becoming a tenured math professor, becoming a pro NASCAR driver results in failure more often than it results in success. So my suggestion is that you marry your ambition and preparation with a reasonable fallback plan. For example my uncle wanted to be a racecar driver but ended up working for a racing company instead managing races after it didn't quite work out in his favor to become the driver. He's loving his job and life, so I think his fallback plan worked. Other fallback plans might involve having some mechanical skills or engineering skills or even just great organizational skills so you can work for a team in another capacity if you don't get to be a professional driver.

So to sum it up: no specific schooling duration is necessary but it still makes sense to use your education to support a fallback plan while you work on improving your driving skills.