For what it's worth, it's my opinion that anything light that stops and steers is a good place to start learning track driving with a good instructor. As in, even 150HP would be fine in a sub-3000# car. The easiest part of the track is driving down the straight, so I'm not really learning much there and I don't care if I point some people by.
It has been my experience that I learn faster in that setup than I do in a heavier, high-power modern car.
It has also been my experience that I prefer something I can comfortably drive to the track -- even a track 6 or 7 hours away -- over something I can comfortably trailer. It just seems easier to drive it. Then again, my towing setup is only adequate, not exactly divine.
Also, Porsche clubs still welcome open top cars but BMW clubs seem to have pretty much quit, and BMW clubs put on some pretty good HPDE schools! It's nice to have more dates on the calendar to choose from.
BMW and Porsche will require you to have equal-restraint passenger seats until you can get out of the first two run groups (and in some clubs even longer).
You will need something quicker once you move out of the first two run groups, but that might take you a summer. Or two. Or in my case, I'm starting my third . . . .
