My DD hates the car too. We find the following things help:
1) We have hung some toys off the capsule handles that she can play with. One of them plays a lullaby when squeezed and she loves it.
2) If both DH and I are in the car, one of us sits in the back with her. This has been the single most effective thing so far, so if there is more than one adult in the car, have them sit next to your baby.
3) DD is breastfed, so if we go for a long drive and she gets hungry but we can't stop, we take a bottle of EBM or a bottle of cooled boiled water to give to her during the drive.

Hope this helps.