its amazing how much a car depreciates in value if you are NOT at fault in the accident. If you hit a wall, funnily enough, it dies not seem to go down as much.
usually the depreciation is calculated as a percentage of the repairs, less the VAT. If the car was very new, sa yonly a few weeks old, then it might be possible to argue the depreciation on the entire car.
how old is your car?
up to 10% of the ex VAT repair figure seems to be the usual rule. However, in UK at one stage, if an old car was replaced with new parts, then the thinking amongst some people was that the car had been bettered and no depreciation was given. I do not think that this argument ever took off here though.