Handling
The Saab has quite a bit wider tires than the BMW 3 Series. Keep in mind that bigger tires can improve handling, while narrower tires may provide better handling in deep snow.
With their comparable turning radii, the Saab 9-5 and the BMW doubtless handle roughly the same into and out of tight spots.
Drivetrain
The BMW 3 Series's engine is quite a bit more massive than the Saab 9-5's. Note that more massive engines may use more gasoline than smaller ones.
Torque equals pickup, and the Saab will have picked up and gone by the time the BMW 3 Series finally gets moving.
The Saab 9-5 packs quite a punch compared to the BMW 3 Series with respect to torque, which is the force that lets you accelerate quickly.
Utility
The Saab is a better choice than the BMW 3 Series in terms of transporting cargo, especially if you frequently need to carry a lot of luggage or big beasts.
Neither the 3 Series nor the Saab has a marked advantage with respect to seating capacity.
Comfort
While the front cabin in the Saab 9-5 offers a bit more head room than the BMW, there honestly isn't much of a difference.
The ampler interior dimensions of the 9-5 make it roomier for your passengers than the BMW.
Dimensions
The BMW 3 Series is a little more ponderous than the Saab 9-5.
Your wallet will hurt more every time you fill up the Saab 9-5 than the 3 Series because of its more capacious tank.
The BMW 3 Series and the Saab 9-5 compete for the same parking spaces.
Cost
The destination charge is a standard charge for transporting the vehicle from its point of origin to the dealer. It costs about the same to get the BMW 3 Series to the dealership as the Saab.
With respect to MSRP, the BMW 3 Series costs approximately as much as the Saab 9-5 (though the Saab 9-5 is a little cheaper).
Overview
The 9-5 and the BMW have the same basic warranty.