Utility
Neither the Mazda MAZDA3 nor the Volkswagen Passat has a marked advantage when it comes to seating capacity.
Dimensions
The Volkswagen Passat is substantially heavier than the Mazda MAZDA3.
Your wallet will hurt more every time you fill up the Volkswagen Passat than the Mazda MAZDA3 because of its more capacious tank.
The MAZDA3 and the Volkswagen Passat 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 approximately the same to get the Mazda to the dealership as the Volkswagen Passat.
As far as MSRP, the Passat costs tremendously more than the Mazda MAZDA3.
The Mazda MAZDA3 is markedly less expensive than the Volkswagen as far as final cost.
Handling
The Volkswagen Passat and the Mazda MAZDA3 have approximately similar tires.
With their similar turning radiuses, the Mazda MAZDA3 and the Volkswagen definitely handle approximately the same into and out of tight spots.
Drivetrain
The Volkswagen Passat's engine is considerably smaller than the Mazda MAZDA3's. Note that a smaller engine usually has to work a little harder; on the other hand, smaller engines typically get better gas mileage.
Torque equals pickup, and the Passat will have picked up and gone by the time the Mazda MAZDA3 finally gets moving.
The MAZDA3 could learn a lesson or two from the Passat as far as torque.
Comfort
While the front cabin in the Mazda MAZDA3 offers a bit more head room than the Volkswagen Passat, there honestly isn't much of a difference.
While the rear of the Volkswagen Passat provides a bit more head- and leg-room than the Mazda MAZDA3, there really isn't much of a difference.
Overview
The Volkswagen Passat and the Mazda MAZDA3 have the same basic after-sale protection.