I am 24 and was on the hunt for my first car, I really wanted an s4, but couldn't find the right price. I test drove the M3, and fell in love. Bought on the spot. The car has been a champ. Pulls off the line like a bat out of hell. The gearbox is smooth and crisp. Brakes are not bad. Sound system is ok, but could be better. Oil changes need to be performed frequently. The car is a lot of fun to drive. You find people want to race you all the time, S4 especially! In the winter get snow tires or store it.
Engine, gearbox, interior feel has a tight closed feeling works well for me being only 5'10.