This home page is a personal account of my own relationship with these strange cars, of which I own one (and have owned two previously). There are quite a few odd snippets of technical information in here, but from my personal view as a Citroën enthusiast and not too much of a mechanic.
Compared to the GS the rear end has been redesigned on the GSA (the GS looks the same but is actually more of a standard sedan with a small trunk), and the interior has been modernised. In particular, the instrumentation deserves mentioning...it's usually perceived as being very futuristic (especially by unsuspecting passengers riding in the car), but after a short period of getting used to actually turns out to be very ergonomic.
Some people have called the GSA and her larger companion, the CX, 'the last real Citroëns', with odd instruments, some totally impossible design solutions, and extreme comfort. When they work it's wonderful - when they start acting up it's a great cause for loud cussing and swearing...
The GSA comes in a several versions. The engine is, just like in the GS, a 4-cylinder air-cooled boxer made by Citroën, and (at least in Sweden) the GSA came with two different engine sizes, though not at the same time. All versions have the possibility of being hand-cranked, not bad for a car made in the 1980's!
Swedish Citroën Car Club has
a homepage with info on the club (in Swedish).