My little one is the same - she screams the house (or car) down. But recently I got a Fisher Price Precious Planet singing mirror and she LOVES IT!! It was the best $50 we ever spent and now she cries till the music comes on!!

Hugs, I hope that he grows out of it soon for you, car journeys with a screaming baby are no fun.
It made me really anxious about going out.

In one of my baby books there is a section on exactly this - and the woman actually suggests that some babies get car sick from travelling backwards. It makes sense.

Sue x