Part of the key to pushing Saab in the crowded and competitive luxury market would be to push the company as having the combination of Audi's rally-bred character with Volvo's thoughtful design. To this end, it would make sense to offer every single car with a versatile all-wheel drive system. Rather than simply adapting a two-wheel drive powertrain to send some power to the other wheels, Saab's AWD should be built from the ground up with a central locking differential.
Were costs of developing such a system too high, Saab has worked with Subaru in the past and Subaru's excellent system (pictured) could simply be licensed.
The rest of the Saab architecture and chassis would have to be designed so that either the two or all wheel drive systems could be installed with as many shared parts as possible.