is it ok to put the car seat in the middle?

Brittany
Is it ok to put the car seat in the middle?
My husbands truck gets super tight with the car seat in. He is trying to convince me that it's safer to have her in the middle because the edges of the seat secure the car seat tightly along with the normal reatraints and if we were in an impact it would keep our seats from squishing her. 
It just makes me nervous...I've always been told to put it on the sides.