According to the Saab History website, the Saab Aero-X will be used as the Autobot Wheeljack in Transformers 2. If you look at the design of the car, you can seem many similarities to the G1 design.
This is considered a rumour for now, but one aspect that backs this up is that Saab is a subsidiary of General Motors, who, if you watched the first film, will know that they supplied most of the vehicle, and will do so again for the sequel.