Someone ran into the back of my girlfriends Renault 5 with a Renault Espace a few years ago. Went to the doctor straight away and he made the suggestion about whiplash and made my girlfriend wear one of those protective collars for a while.
Got £300 for the Renault (you can imagine what sort of a car it was) straight away as it was a write off but the case for the whiplash went on for ages. After about a year my girlfriend finally got a payout of £2000 which definitely made it worth while and ment her new car had cost her £2300 less than it would of done. Added to this the months of hire cars (seemed to be a different brand new car to redline every week) and all in all it was pretty good for her.