My Alex was the same. Absolutely HATED the car. Even with dummies, feeding during driving, everything... nothing worked. Had to just let him scream.... awful feeling.

I ended up turning him around at 5months (he wasn't really big enough though and looking back at it I probably shouldn't have) and he LOVED the car. Seems like he just hated being backwards!

I just avoided the car for the first five months unless unavoidable... so don't really have any tips... unless one of you sits in the back and shoves the dummy in his mouth thousands of times...

Or can you fly?

HTH.