Legal Question in Personal Injury in California

The insurance company will pay the LESSER amount of either: a) the cost to repair; or b) the fair market value of the car. That's it-- your permission is not required. If scenario (b) ends up being the case, that's what we call a "total loss" and you have no choice in the matter. You can decide to keep the car, but you will have to get a "salvage" title, which basically makes the car unsalable. If you plan on driving the car yourself until the wheels come off, then that's fine. I've seen plenty of people decide to do that. You will be paid the fair market value minus the "salvage" value of the car (which is the amount that the car is worth as scrap). You just have to tell the company that you intend to "retain salvage."

An insurance company is not obligated to pay more than a car is worth to repair it, just because you want to keep it, or because you put a lot of money into it.