BMW has stretched the wheelbase of the 3 Series sedan to offer more rear-seat space. Has this diluted the fun of the sports sedan or have they perfected it even more? We pitch the new 3 Series Gran Limousine or the 3 Series Long-Wheelbase, against the regular 3 Series sedan to find out. For this comparison, we pitched the diesel versions of the sedan, 320d spec, and drove them back-to-back to come to a concrete conclusion.