You cannot appeal a binding arbitration decision. The main reason one goes into the arbitration in the first place is because the two parties couldn’t agree on a fair auto accident settlement in the first place.
However, you could challenge an arbitration award in court IF the award is related to the arbitrator’s corruption, fraud, or misconduct. This would be a difficult and expensive thing to prove however. You would definitely need to hire an attorney, and possibly a private investigators. Arbitors are typically former judges, and are usually not going to risk their careers over helping one side over another in a car accident arbitration. As a result finding any sort of fraud or corruption on the part of an arbitor will be very difficult.
The best thing to do if you’ve been injured in an auto accident is try to come to terms on a fair out of court settlement for your auto accident injuries. If that won’t work and the claim does end up in arbitration, it’s best to assume that the arbitors’ decision will be final.