I've been pulled twice in the 370Z, once for a minor, 36 MPH in town, hand-held radar-gun type deal, the other for a very similar situation. He had me bang to rights but wasn't in a car with any speed measuring equipment.
I did the right thing like you - confessed immediately and apologised profusely. He gave me the commensurate talking-to then took a step back from the car and said "Nice car though, it is late a night and there isn't much around. I can see why you did it."
What a nice copper!
Most traffic cops are petrol heads, so they know the score. Just don't drive like a total dick and if you do get caught, have the good grace to take it fair and square.