For their assembly plant? They will not expect you to know anything about cars but be prepared to talk about team attitude and how you play a part in that and also, if they like you you will go on to further testing.
my mom works at Honda on the assembly line. she said she had to take a test to see where they place you. i wouldn't worry about dressing too fancy if that's the job (assembly) you'll be doing. and no, you don't have to know everything about cars. there are some really stupid people who work there lol (my mom has told me some crazy stories).