Couple of things to do before accepting the insurance company's check for a totaled vehicle:
1. Ask for the local market research documents from which the derived the vehicle's value.
2. Many states require that companies turn them over when asked, in other places you might have to be insistent.
3. Examine the market research carefully looking not merely for equal comparisons in terms of age, mileage and condition, but also to see if they rigged the results by pulling quotes from a cheaper area.
4. Write out some talking points as to why you should get more, and go back to the insurance company with them.

From here:
http://volokh.com/2011/02/12/lessons...oss-valuation/