Re: My Autistic child will not stay in his carseat...
First, I just wanted to give a finding out that you have a special needs child is so difficult.
That is tough spot for the car. My BFF has two children with autism and the older one was so hard in the car. I don't have any great advice other than stopping right away and fixing the straps as many times as it take which could be MANY I just wanted to mention that she needed her DD to be in a harness for as long as possible so she bought the Britax Regent which has now been replaced by the Frontier 85. That would give you the longest harness use without getting into special needs seats that are $$$$$.
Just in case.