Hi there. First of all, welcome to YT and congrats on your baby.
There are a couple of thing you can try. 1) I got a snozzer car seat for mine and it help Hot Rod right away, he stopped getting carsick. It was the not being able to focus while you are in motion probelm he was having.
Maggie May would still get carsick but once she discovered she could sit/stand up and look out the window she didn't get carsick any longer-so I am not sure if it was over time or that she finally started looking out the window. Poor baby would get soooo sick! The day we brought her home, she threw up the 45 minute car ride home. and she would get sick on the boat too.
2) there are over the counter things that you can get to help/your vet can give you some ideas as well as dosages.
3) you can try giving ginger snap cookies 1/2 hour before driving.
4) start slowly and take your baby out for short trips (like the driveway and back) several times and increasing the time out to him used to being in the car and the motion. Stop before he gets sick.
Best of luck to you and him!