This is a tough question with no easy answer. Some people think the depreciation is a percentage of your repair bill. Some argue that if your car is repaired correctly there’s no depreciation. With online vehicle-history listings (e.g., CARFAX), someone can always see if your car has been wrecked and repaired and it’s simply not worth as much. Likewise, we have all seen the red or grey car that has had a fender repainted that doesn’t really match, and time only makes it more obvious. (I’ve never understood why grey was so hard to match. But I digress.) In a perfect world, I would get the dealer who you bought it from to reappraise your now-wrecked and repaired car and tell you what they would give you in trade for it now, compared to what they would have given you the day before it was wrecked. That’s the true depreciation number.