

Something that happened in South AFrica about a year ago: A dealer sold a 
Mercedes with an odometer reading of 150K kilometers to a lady. Turned out 
that the actual reading should have been 160K. Court case followed because
lady said she wouldn't have bought a car with that much km's. Dealer found 
quilty, fined and had to take back the car.

I think you have a case if you can get a sworn statement from the previous
owner. Take the car back to the dealer and threaten him or something.