Not that far fetched, I know ALOT of people that add a container at every fillup....on their DIESELs(specifically 7.3 and 6.0 powerstrokes).
I wouldnt recommend adding it to your gasoline powered vehicles.
I have heard and seen it on a few occasions where running a bit of ATF can clean things up due to all the "detergents", but I still wouldnt recommend it on a modern engine. An old carbeurated farm truck? Sure, throw whatever you want in there, but probably not the best idea on a new ride(granted that E46's arent that new anymore).
Last edited by Rubenk; 02-12-2013 at 07:26 AM.