Try sea sickness tablets
Sturgeon are cheap and available from most chemists and supermarkets take one before you go to bed and one in the morning with a light breakfast before a lunchtime drive and see how you go the next step up is two tablets (recommended dose)
Get someone else to drive you in your car and try a scopdoderme patch this is for when you are so sea sick you are unable to hold down any tablet formed medication and are in danger of loosing to much fluids due to sickness.
This could train your brain that the car is ok as it should remove the motion sickness and get you used it
Always check with your doctor/ pharmacy first
If you need to drink take small sips multiple times rather than a good swig of something not too sweet
Also turn the radio off
The first time I sailed to France overnight in a gatefold 8 in a 36ft yacht I was very badly ill so bad I did not want to come back but I was advised to try Stugeron and I have never been sick since and don’t need to take them now
Hope this helps