Until the heads up test, I thought this Car and Driver article was interesting. It matches the Cayman S (old one) against the BMW Z4M. The BMW appears on paper to be a close match to the Z. Check it out....
A quick run through the 3303-pound M-car's gears produces a 0-to-60 time of 4.8 seconds, a quarter-mile time of 13.4 seconds at 105 mph, and a governed top speed of 160 mph. The Cayman S rang in at 4.8 seconds to 60 and posted a slightly quicker quarter-mile time of 13.3 seconds at 107 mph on its way to an ungoverned top speed of 166 mph.
2006 BMW Z4 M Coupe vs. Porsche Cayman S - German Performance/High Performance/Hot Lists/Reviews/Car and Driver - Car And Driver