I think most countries have some kind of official or well know appraisal organizations which give official book values for vehicles which are used by the general public as a guideline for buying and selling, and by insurance companies for calculating payouts when cars are wrecked.
Let's say I want to sell a older car ( say 15 to 20 years old ) according to it's book value. What kind of assumptions go into that book value? Does it assume that everything in the car is basically in perfect condition, just old, or does it assume the normal kind of wear and tear a well maintained car of that age would have, like small oil leaks, worn out shocks, minor dings and dent or slightly faded or oxidized paint, etc...
If I'm trying to sell such a car according to book value, what are my obligations as far as pointing out what I would consider normal wear and tear in my region? I say in my region, because the typical practice here is that people do the absolute minimum as cheaply as possible to keep the vehicle street legal. This goes back of course to what assumptions go into the book value. Do I need to point out every little problem or potential problem I'm aware of, or can I ethically simply say that the car is in good condition for it's age and list the specific repairs I've done to it?
Where do you draw the line between trying to be a salesman, since of course you want to sell your car for as much as you can get, and making sure you are not being dishonest?