BMW recently pulled the wraps off of its hot new 1 Series M Coupe, but this new addition to the automaker’s least expensive range isn’t the only changes on tap for the 2012 model year. Both the coupe and convertible versions of the 128i and 135i receive modest upgrades for 2012, including very, very slight styling updates and a new powertrain for the 135i.Up front, 1 Series cars equipped with
