Nothing.
This is my dad's car. When his nissan stanza broke down, he was looking for cheaper cars. But when his curiosity brought him to test drive this car, he had to buy it.
I ask him everyday to drive it, and when I finally did, I was stunned. I fell in love with it, I am looking for a same model, but 1991 or 1992. It is fast, has many good features, has great handling, and smells good. The only thing I do not like about BMW's is they are hard to get used to, due to all the feature's. But when you get used to it, you will find out why they call it the ultimate driving machine.
The 325i is an inline six.