Date the car was built on
In case you don't know how to find when your car was built....
Look on the drivers door on the inside - the bit that goes down from the lock. Look near the bottom. You should see a paper label which has the month and the year clipped out of it. It will tell you when the body was first assembled and painted, and is the best way of determining real age.All cars sold in the EU MUST have this by law. If not on the drivers side, look on the passenger.
Your dealer can tell you when the car was built to the hour if you ask him nicely.