My 4 month old baby gets histerical once I put his infant carrier in the car. He won't stop crying turning blue and shaking. What should I do?

Keep him safe in car. At four months he is too young for a real temper tantrum. While he may get agitated by the car seat's restrictive environment, his safety in the car is paramount for him to be transported in any other way in the car. You may want to have someone else sit beside him not to make him so lonely.
Check the seat. same thing happen to my daughter we were going on trip and we bought her brand new car seat she will not stop crying until we actually drove back 50 miles home to get her the old seat my advise check the seat make sure there is nothing in it make your baby uncomfortable like blocking his view or not be able to see you or if there is something in the seat that pocking him good luck.