Cost
The Dodge Caliber is quite a bit less expensive than the Mazda MAZDA3 as far as MSRP.
The Dodge isn't much less costly than the Mazda MAZDA3 with respect to out-the-door price.
Utility
The Dodge Caliber's bigger trunk will accommodate more big things than the Mazda MAZDA3.
Neither the Caliber nor the Mazda has a marked advantage when it comes to seating capacity.
Comfort
While the front cabin in the Dodge Caliber offers a bit more head room than the Mazda MAZDA3, there really isn't much of a difference.
The Mazda MAZDA3 is not particularly roomier for your passengers than the Dodge Caliber.
Dimensions
The Dodge Caliber is likely to feel a little slow because of its high horsepower-to-weight ratio compared to the Mazda MAZDA3.
The Dodge Caliber's tank is roughly the same size as the Mazda MAZDA3's, though the Mazda MAZDA3's is slightly more capacious.
The Dodge Caliber rides lower than the MAZDA3, which is a good thing for its center of gravity and ease of access.
The Dodge and the Mazda MAZDA3 compete for the same parking spaces.
Performance
The Dodge Caliber is likely to feel somewhat slow because of its high horsepower-to-weight ratio compared to the MAZDA3.
Handling
The Dodge Caliber and the MAZDA3 have approximately similar tires.
Drivetrain
The Dodge's engine is significantly smaller than the MAZDA3's. Note that smaller engines can be stressed more; on the flip side, smaller engines are often cheaper to fix.
Torque equals pickup, and the MAZDA3 will have picked up and gone by the time the Dodge Caliber finally gets moving.
The Caliber could learn a lesson or two from the Mazda MAZDA3 in terms of torque.
Overview
The basic warranty that comes with the Dodge Caliber isn't quite as generous as the Mazda MAZDA3's.