Ultimate driver's car? Well it has to do a number of things.
First, it has to have satisfying, feelsome controls. Which rules out most things with a flappy paddle gearbox or electric steering. It must sound fantastic, the exhaust note and intake roar must combine to bring a big smile to the face of the driver, so anything with a four cylinder and most things with a v6 are gone. It must have a surfeit of power, but not so much that it is intimidating for the weekend enthusiast (which most of us are). So that eliminates most of the current breed of hypercars, and certainly stuff like the McLaren F1, and it eliminates stuff like the MX5 or S2000. It must handle with precision, immediacy and delicacy, which takes away pretty much all the musclecars (be them German, American, English, Australian etc).
So you know what it is then? The ultimate driver's car? Well, it has a proper manual gearshift, operated through one of motoring's design icons, the milled h-pattern gate. It's small, and compact, so it's nimble. It has enough power to satisfy, but delivered in a sensible, linear fashion (IE not in a big diesely lump or in a turbocharged rush which could be difficult to meter out). It has the kind of engine note that makes you want to go looking for tunnels, or downshifting alongside rock-walls. It comes from one of the most evocative names in the motoring world.
It's the Ferrari 355.