The McLaren 650S Spider costs some £20k more than the £190,000 coupe version, and it’s worth every penny. Why? Because it can do just about everything the coupé can do dynamically yet adds a sizeable hit of extra sex appeal to go with it. And that arrives courtesy of a folding hard top roof that can glide up or down in but a few seconds, and which transforms the 650S into an even more exotic creature on the move. Steve Sutcliffe puts it to the test.