No way on the planet BMW sells hundreds of thousands of 1's a year.
By way of example, this release from June shows Toyota sold 21k Camrys in the month. Annualized that equates to about 250k units per year for the best selling car in the US!
I can't find exact sales figures but I bet Toyota sells at least 9 Camrys for every 1-series BMW sells.
http://pressroom.toyota.com/releases...2011+sales.htm
As you said large auto makers do sometimes sell low-volume cars that may lose money for what's called the "halo-effect" that will hopefully improve the public's view of the brand & ultimately sell more minivans and Malibus (think Soltice, Viper, NSX, etc.).
I'm just not sure this car is cool or interesting enough (again think Soltice & Viper & NSX by comparison) to bring large numbers of people into the dealership or end up generating publicity on TV, internet, in magazines, etc.
Might end up being a nice car but I'm just not sure its a smart business move from a sales or halo perspective. Of course it is GM so smart business decisions are not exactly their specialty.