As far as the S197 GT and GT500 go, the 13/14 cars are by far the best. They don't have all the issues the 05-09 cars do. 11/12 cars are good too. But a 13....get it if the price is right (21-24k with that mileage). The IRS on the S550 is nice, but not all that much nicer than the 3-link S197 cars.