Agree the Cayman is competitive with an NA E90. You get a different satisfaction from either. With the Cayman less is more. With the E90 it's fun to rip to the end of a track with a rumble. M3 can achieve a higher peak speed but is not faster in lap time necessarily - if peak speed is what satisfies you the Cayman will NOT cut it.
I say think both of those cars have caveman engines at this point. A software driven turbo engine is the future. We buy these cars to get a thrill. The M3 with an ECU flash is going to deliver a giant shit eating grin to my face. Putt-putting around in a Cayman is a nostalgia I don't share. I get it, I just don't want to pay $80k for the privilege of less is more.
There is no greater thrill than watching the speedo skip 8 MPH at a time at over 90 MPH. 95 to 130 down the front straight in 4 seconds is the thrill I want. And I'm going to get it with this M3.
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WTB: 2016 M3 sedan, Black Sapphire, Extended Sakhir Lether, Ceramic Brakes, 19" black wheels, Lighting Package, HK sound, USB/Bluetooth
Sold: 2006 e90 325i 6MT, ground control coilovers, Remus exhaust