It's not really based on any car, but borrows a lot of parts from the Volvo 960.
The rear suspension (multi link axle and the mentioned leaf spring) is straigt from the Volvo. The spring is also used in the front, but the front axle is a construction of their own with doubel aluminium wishbones..
I think more parts, like gearbox, steering, electricity etc comes from the Volvo as well, but I'm not sure. As mentioned, the engine is from the Volvo.