Once you agree to a settlement and take back possession of your vehicle you usually can chose to get it fixed or sell it for parts or do as you please. This is if the settlement check is made out to you and not you and a second party (like the auto repair shop).

When negotiating your settlement should get your repair estimates together to make sure that you can pay to get the car repaired if you decide to do so.

How to Deal with Insurance Adjusters is an article you might find of interest.