Utility
The Audi A3 will quite certainly prove more practical than the BMW 328 for those of you with frequent kid-cargo.
The Audi is likely a better choice than the BMW 328 in terms of transporting cargo, especially if you frequently need to carry a lot of cargo or big pets.
Performance
In terms of horsepower, the 328 packs quite a wallop and will knock the Audi A3 down a few rungs. On the other hand, keep in mind that high horsepower engines often command higher insurance premiums.
Dimensions
The Audi's tank is approximately the same size as the BMW 328's, though the BMW 328's is somewhat bigger.
The Audi and the BMW 328 compete for the same parking spaces.
The A3's shorter wheelbase may produce a less-settled highway ride but a more maneuverable feel in daily traffic than the BMW 328.
Convenience
You will definitely have to visit your friendly gas station more often with the 328 than with the Audi.
Cost
The Audi A3 will save you money at the pump compared to the BMW 328.
Regarding gas mileage, the Audi has the BMW 328 beat.
The BMW 328 is significantly costlier than the A3 when it comes to MSRP.
The Audi A3 will save you a lots_of_money at the pump every year compared to the BMW 328.
The BMW 328 will cost you a lots_of_money in gas every year compared to the Audi A3.
Handling
With their comparable turning circles, the Audi and the BMW 328 likely handle almost the same into and out of tight spots.
Drivetrain
The BMW 328's engine is considerably larger than the Audi A3's. Keep in mind that more sizeable engines may use more gasoline than smaller ones.
The BMW 328 has no lessons to learn regarding torque from the Audi A3.
Torque is roughly equivalent to acceleration, and in this respect, the Audi A3 isn't much more powerful than the BMW 328.
Comfort
While the front cabin in the Audi A3 offers a bit more head room than the BMW 328, there really isn't much of a difference.
While the rear of the Audi provides a bit more head- and leg-room than the BMW, there honestly isn't much of a difference.
Warranty
The A3 and the 328 have the same basic after-sale protection.