Handling
With their similar turning radii, the Cadillac CTS and the BMW 3 Series likely handle roughly the same into and out of tight spots.
Drivetrain
The CTS's engine is quite a bit more sizeable than the BMW 3 Series's. Remember that more sizeable engines may use more gas than smaller ones.
Torque equals pickup, and the Cadillac will have picked up and gone by the time the BMW 3 Series finally gets moving.
The 3 Series could learn a lesson or two from the CTS regarding torque.
Utility
There's no clear winner between the Cadillac CTS and the BMW 3 Series with respect to hauling capacity.
Neither the 3 Series nor the Cadillac CTS has a marked advantage with respect to seating capacity.
Convenience
You doubtless won't have to visit your friendly gas station more often with the Cadillac CTS than with the BMW 3 Series, because both offer similar ranges.
The Cadillac's fuel tank will need to be replenished a little more often than the unit in the BMW 3 Series.
Comfort
Taller drivers will markedly enjoy the extra head room in the Cadillac's front cabin compared to the BMW.
The Cadillac CTS is not particularly more spacious for your passengers than the BMW 3 Series.
Dimensions
The Cadillac CTS is a bit heavier than the 3 Series.
The BMW 3 Series's tank is approximately the same size as the Cadillac CTS's, though the Cadillac CTS's is a little larger.
The BMW 3 Series and the Cadillac CTS 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 roughly the same to get the 3 Series to the dealership as the Cadillac.
The Cadillac CTS will tax your gas budget markedly more than the BMW 3 Series will.
As far as fuel economy, the BMW and the Cadillac CTS don't differ much.
The Cadillac pales in comparison to the BMW 3 Series regarding gas mileage.
The BMW won't save you much money at the pump compared to the Cadillac CTS.
As far as MSRP, the BMW 3 Series costs quite a bit more than the Cadillac.
The Cadillac CTS isn't much less expensive than the BMW 3 Series regarding out-the-door price.
Overview
The Cadillac CTS and the 3 Series have the same basic after-sale protection.
Other
The Cadillac CTS produces fewer smog-forming pollutants per 15,000 miles than the BMW 3 Series.