Alpina are manufacturers not tuners, the German governing body has a loophole which allows Alpina to be classed as a manufacturer, they produce low volume cars which are titled Alpina as opposed to BMW.
They have their own chassis number besides the chassis number of BMW. Alpina chassis numbers usually start with WAP........

http://www.unixnerd.demon.co.uk/alpina.html

List of automobile manufacturers

http://en.wikipedia.org/wiki/List_of..._manufacturers