AITAH for telling my 17 year old stepson and his mother that he can't ride for 14 hours in my car unless he takes a shower?

That's right. It's been 3 weeks since he has bathed and washed his hair. He only brushes his teeth once a week and does not wear deodorant. We are planning a trip to UTAH and it's 14 hours. Absolutely no way in hell am I going to smell a teenage boy that is 3 weeks past ripe, the entire trip. He's a good kid but his mother says that it makes him have his own Individualality and express himself. WTF?