The problem is selling a car that's got a writeoff title is something most people aren't comfortable with. All the other little things aside unless you knock a fair bit off your asking price that buyer probably isn't going to buy it now that he knows it's been written off at some stage in its life.

You really need to know more about what happened to that car. Maybe it was stolen, joy ridden + light accident (bog) and someone blew the engine, stole the seats. In this case since repairs are quoted by insurance using new parts, it doesn't take much for the repair bill to exceed 2/3 the market value. It's still probably an ok car after the repair.

On the other hand if it's had a major accident and someone fixed it, it's a lot less desirable since potential buyers are worried about chassis integrity and quality of the repair etc.