Jake has already pointed out a great deal of information about these little car's so not much more I can add.
I will say this, these are not " VW Kit " car's , they are produced by a large manufacturing company in Brazil that has been making them since the 50's as replica's. They use a full frame and have a mid mounted engine, not a pan based frame using a rear mounted engine.
There was a company that made a VW based 550 it was called Perry and they show up from time to time.
The car's do use some VW type part's, my car is using a type 1 block and making 120 HP which is more than enough in my car which weighs less than 1000 pounds fueled with me sitting in it.
I use front disk and rear drum brakes, out of all my car's it get's the most attention both on and off the road, people always want to stop and talk.
A great site to check out for info is
www.spyderclub.com
Todd