MY dad loves my boyfriend like a son! 10 points!?

It sounds like they have a lot of the same interests. Do you have any brothers or sisters who are into cars? If not, I think your dad just misses having someone to talk to who shares his interest. Maybe you should ask to join their conversations, or get your boyfriend to teach you about cars, then you and your dad will have that in common. Or just leave it alone- your dad is happy, your boyfriend seems to be happy, and it's better than having your dad hate your boyfriend.