Vehicle insurance is also known as auto insurance or car/motor insurance. It refers to insurance that consumers can buy for their cars and other vehicles chiefly to protect against any loss that they might incur due to traffic accidents. It is the auto insurance claims adjusters that usually establish a car's actual cash value utilising the prices in their company's proprietary database. An insurance company may even declare a vehicle as completely destroyed (that is, 'totalled' or 'a write-off') if replacement seems to be cheaper than the vehicles actual repair. Companies total vehicles at different values- some at 51 percent of the car's actual worth while others at 80 percent. The company generally pays the car's actual cash value, less any deductible on your coverage. The insurance company usually auctions off the car at a salvage yard and mostly chopped up for parts. It is important to note that there a different policies available and these stipulate the conditions under which each insured item is covered. For instance, a vehicle may be insured against fire, damage, theft and accident damage independently.
Whenever your car undergoes damage, it is send to a network garage. The garage person then assesses the damages and the same is conveyed to the insurance agent of the insurance company. Now based on the model and the age of your car, there is a standard formula for the depreciation for the car and for the parts calculated. After the depreciation the insurance company then reimburses you for the claim.
I think it's important to note that the insurance companies don't quite estimate the damage. They send the car to a workshop and let the car workshop estimate how much it will cost to replace parts. Then they'll calculate your excess and all that and tell you how much they will let you claim.
Here's a pretty good link:
http://www.iii.org/article/how-are-value-my-car-and-cost-repair-determined
And just a comment---state laws have rules about when a car is "totaled." That's why there is a category called "salvage" titles.