Well, this is a complex issue, but there's a few simple things:
Socket: you buy a car because you want a car. I agree, that if you are purely in search of performance, regardless of form, then you bet a bike, but saying why bother with a fast car is exactly the same as saying why bother with a mtb, especially when you can get a MX bike for the price of a top DH rig, have more travel, jump bigger and go shitloads faster. They are two completely different entities, both with their own merits, and shouldn't be compared like this; but in the intrest of comparisom, a bike would only be a second vehicle for me because: I can carry heaps of stuff in my car, including my pushy, I can carry other people in it, I can sleep in the back of it (thank god for that), and when it starts to piss down outside I can stay nice and dry inside (and so can all my stuff).
To anybody who's going to go:
"maaaaaate, those little turbo things are so crap, you gotta have a big V8 donk up front, flanno in the drivers seat and a slab on the backseat"
or alternatively :
"oh bro, my hot 4 so shit's all over those bogans in their V8s man. It's like fully sick ya know?"
PULL YOUR HEAD OUT OF YOUR ARSE! Fast cars come in all shapes and sizes, some rely on forced induction, some rely on huge capacity and some rely on all sorts of gizmos, but they all put out large amounts of power. If you prefer one sort for whatever reason great, you buy one of them, but at least learn to appreciate that althought some V8s might rely on dinosaur technology they can still get the grunt, that's impressive. Also very impressive is the amount of power that comes out of the atmo 6 in the M3, or the speed and value of something like a WRX.
Now back to the topic...I don't think I'd ever drive around in something with a huge bodykit and neon lights, no matter what was under the bonnet; can you say "cop magnet"? But by the same token I'd rather not drive around in something that looks like it just got into a fight with a mack truck, they also attract lots of attention, for defect purposes.
My own tastes lean towards something that is clean and straight, but low key. Interior though is another matter. I would much prefer to have something that is closer to the limo end of the spectrum. Like said previously, cars are more comfortable than bikes, so why not make them as much so as possible?
What I think I would really like though, is something along the lines of an HR, maybe ute, relatively stock on the outside, but with sorted suspension and brakes, and maybe a V6 or something under the bonnet (you don't need huge amounts of power) and with a nicely redone modern style luxo interior. Something with some understated style.