Cost
The destination charge is a standard charge for transporting the vehicle from its point of origin to the dealer. It costs almost the same to get the Cadillac STS to the dealership as the GS 450h.
Producing an accurate fuel economy evaluation is so tough that some think not even the federal government can do it, but it looks as though the Lexus GS 450h is the winner with respect to gas mileage.
The Cadillac STS won't save you much money at the pump compared to the Lexus.
As far as MSRP, the Cadillac STS doesn't cost much less than the Lexus GS 450h.
Utility
Neither the STS nor the GS 450h has a marked advantage regarding seating capacity.
Convenience
The Cadillac STS's fuel tank will need to be replenished a tad more often than the unit in the Lexus GS 450h.
Comfort
While the front cabin in the Cadillac STS offers a bit more head room than the Lexus, there really isn't much of a difference.
The Cadillac STS provides more head- and leg-room to your passengers than the Lexus GS 450h does.
Dimensions
The Lexus GS 450h is significantly heavier than the STS.
The Cadillac STS's tank is almost the same size as the Lexus GS 450h's, though the Lexus GS 450h's is slightly bigger.
The Lexus GS 450h and the Cadillac STS compete for the same parking spaces.
Handling
With their comparable turning circles, the Lexus GS 450h and the STS most certainly handle roughly the same into and out of tight spots.
Drivetrain
The STS's engine isn't much bigger than the Lexus GS 450h's.
Torque is the force that lets you accelerate quickly, and in this respect, the Cadillac STS isn't much more powerful than the Lexus GS 450h.
Warranty
The Lexus and the STS have the same basic after-sale protection.