As a guy who has hired for the Automotive Industry for dealerships, manufacturers, corporate and private collision centers I will give you some advice. Don't overthink it. Khakis or dress pants and a nice button up are fine. Heck, if you want to impress, walk in with a suit jacket.
Don't forget the simple shit like showering and shaving which is unfortunate I have to mention that these days. I've hired the nicely dressed that failed me and the poorly dressed that amazed me.
Good luck and don't nervously talk or get to animated.