You know, one of the keys to good conversation is listening. So often people spend time in conversations waiting for the chance to say their ‘thing’, or trying to think of something to say. I actually do also see it on sites like this one, where so many posters tell their story or give their opinion without paying heed to what others are saying.
If he is interested in cars or building, how would he react if you were to ask him to explain something or give an opinion on something to do with those things, and then really listen to what he has to say? Okay, it may be a bit of an effort, but might lead to an interesting conversation.