I never take a loan to buy a car or motorcycle, but I have written off a few vehicles (all my fault, and none involving other people. One amusing-in-distant-hindsight-only case was when I spilled paint all over the interior of a car, written off by the insurance company as beyond economic repair).

In each case I only got the value of that vehicle as per the lowest price the insurance adjustor could find, taking the mileage and age into account. That was never enough to buy something of equal value to me, and I assume totally inadequate to pay off the outstanding loan amount.