Performance
With that kind of horsepower, both the 750 and the Cadillac STS are true sportscars.
Regarding horsepower, the BMW packs quite a wallop and will knock the Cadillac down a few rungs. However, note that high horsepower engines often command higher insurance premiums.
Handling
With their similar turning radii, the Cadillac STS and the BMW 750 most certainly handle roughly the same into and out of tight spots.
Drivetrain
The BMW 750's engine is considerably larger than the Cadillac's. Remember that larger engines may use more gas than smaller ones.
The Cadillac STS could learn a lesson or two from the 750 in terms of torque.
Torque equals pickup, and the BMW 750 will have picked up and gone by the time the STS finally gets moving.
Utility
Neither the 750 nor the Cadillac STS has a marked advantage regarding seating capacity.
Convenience
The BMW's fuel tank will need to be replenished a little more often than the unit in the Cadillac STS.
Comfort
Taller drivers will considerably enjoy the extra head room in the BMW 750's front cabin compared to the STS.
While the rear of the BMW 750 provides a bit more head- and leg-room than the Cadillac STS, there frankly isn't much of a difference.
Dimensions
The BMW 750 is significantly more bulky than the STS.
Your wallet will hurt more every time you fill up the 750 than the Cadillac STS because of its larger tank.
The Cadillac and the 750 compete for the same parking spaces.
Cost
In terms of gas mileage, the Cadillac STS bests the BMW 750.
The 750 uses a lot of gas compared to the Cadillac STS.
As far as MSRP, the BMW 750 costs tremendously more than the Cadillac STS.
The BMW 750 will cost you a lots_of_money in gas every year compared to the Cadillac.
Warranty
The STS and the BMW 750 have the same basic warranty.