Utility
The BMW 328 and the Audi A5 can accommodate the same number of passengers.
Dimensions
The BMW 328's tank is roughly the same size as the Audi A5's, though the Audi A5's is a tad larger.
The BMW 328 and the Audi compete for the same parking spaces.
Convenience
You quite certainly won't have to visit your friendly gas station more often with the BMW 328 than with the A5, as both offer comparable mileage ranges.
Cost
With respect to fuel economy, the BMW 328 is a bit better than the A5, but not by much.
As far as MSRP, the Audi A5 costs substantially more than the BMW 328.
Handling
With their similar turning circles, the BMW 328 and the Audi most certainly handle almost the same into and out of tight spots.
Drivetrain
The 328's engine is substantially larger than the Audi's. Remember that larger engines may use more gas than smaller ones.
The BMW 328 could learn a lesson or two from the Audi A5 when it comes to pickup.
Comfort
While the front cabin in the Audi A5 offers a bit more head room than the BMW, there really isn't much of a difference.
The ampler interior dimensions of the 328 make it roomier for your passengers than the Audi A5.
Warranty
The Audi A5 and the BMW 328 have the same basic after-sale protection.