There were rumours a while back that Saab would be tackling increasing emissions restrictions by moving to smaller displacement engines. It looks like there's some truth to that. Recent reports indicate that the next Saab 9-5 will offer an engine as small as 1.6 litres, turbo-charged of course, in an effort to comply with both emissions standards and performance requirements.
Dimensions will be up, as the 9-5 will share the Epsilon II platform underpinning the current Opel Insignia, but don't expect performance to slip. Saab will continue utilising BioPower engines to keep consumption down and motivation up. Saab's BioPower engines are E85 compliant, with a high-pressure turbo bolted on for good measure, and installed in vehicles with AWD.
For those to whom size really does matter, there should be a 2.8L V6 and at least one diesel on offer to satisfy your needs.