Car Pulling To One Side?

So I have a 2006 BMW 325i E90 and it has something wrong with the steering. My first thought was obviously alignment but when I realised it wasn't happening all the time, I thought again. Essentially I can be driving down the road and take my hands off the wheel and it keeps driving straight without a... show more So I have a 2006 BMW 325i E90 and it has something wrong with the steering. My first thought was obviously alignment but when I realised it wasn't happening all the time, I thought again.

Essentially I can be driving down the road and take my hands off the wheel and it keeps driving straight without a problem....but then sometimes it will keep trying to veer to the left. Sometimes it's gradual and sometimes it really can be quite sudden and sharp.

Any suggestions as to what this might be would be greatly appreciated
3 answers 3