You're interested in cars? Interesting. Make videos about cars.
What else do you want me to tell you?
If you're legitimately interested in working with cars, there shouldn't be any second thoughts. Teach people what you know about cars. Get them excited for automobiles. Keep up with the latest news.
If you're going to do YouTube, do it on something you're legitimately interested in. If you try going for the popular genres you're going to fall flat on your channel.
Otherwise. To answer this question.
Comedy, gaming, sketches, short films, etc.