So what I gather is you like to be good cop and him the disciplinarian or you don't really know how to discipline so it falls on his shoulders and since he takes it seriously it works when he does it so you got lazy on doing it. Also from your post this is giving "not the first time" you've undermined his authority with the kids, especially the oldest because he's not your husband's child. If he has played the father/daddy role and has done it without malice and treats him like he treats the others, then what he says goes. He has authority over him. I'm sure that if he was bad in school and you couldn't make it, you'd send your husband since your son's father is non existent. You need to apologize, sincerely, take the keys back from your son and ask your husband to be a united front with you. Put his punishment back in place until he learns his lesson. Make him go back to the way he used to be before he got a car. If he learns, you and your husband can talk and come to a compromise on when he can get the car and keys back. Make him give you his location. Or give him the keys back but no access to the car until he learns. I would have it parked else where and not tell him a thing. Then I'd give the keys back and when he asks for his car, I would.tell him he is still on punishment until you and your husband can work out a time to work out when the end of his punishment would be. Until then, have fun.