I have a 2011 Golf TDI. It's not nearly as cold where I live as it probably is where you are, but on a 30F morning, my temp gauge is at normal after 3 miles of stop and go across town driving. The heated seats put out serious warmth within the first block, and there's some kind of electric heater in the vent system because it will start blowing warm air within a few blocks. So commuting may not be all that awful even in colder weather. That said, the miles I drive have been dropping and I'd probably be better served with a GTI. The diesel torque is nice, but it's a car that shines on long drives more than short trips. For the driving you describe, I'd stick with a gas engine, honestly.