BMW 3系 4 years free maintenance is good

You have option to spend around $1600-$2000 to buy additional two year free maintenance.

The maintanance include brake change which usually cost $1300-1500.

In terms of reliability, they are more and less same. 

BMW is more fun, handling is better and rear wheel drive. Audi 4 is bigger, but negative side is front wheel drive, which you could get from most of regular cars.