I've had mine pretty closed to terminal speed at 163 mph. That was clocked on a radar gun in northern michigan under "fairly" controlled circumstances. I think it only had a few more mph before it was really topped out. Probably closer to 170 given enough straight pavement. But at that speed even a worm will throw you off your line and make it wiggle! Either way, I've embarrassed more than a few v8's, with a big 'ol grin the entire way! By the way, My aunt's '87 jaguar xks, with the 12 cylinder, has no guts at all!