No garage, but I do have a Honda Civic in my driveway. It's an HX which gets 35mpg in the city and 40mpg on the highway. And no, it's not a hybrid. Because of its low emissions and low fuel consumption rate I don't feel too bad about driving it a few days a week when I'm not riding my bike to work. Eventually I will ride my bike a lot more. Just need to hook myself up with a rear rack and panniers so that I don't have to deal with my cumbersome backpack (which leaves me with a rather sweaty back).

So to answer your other question, I'm bike commuting about twice a week out of desire. It started as a way to get some exercise on my non-running days, but lately I've been seeing big dividends from the enjoyment factor and the gas savings. Someday in the near future I may be using my Civic only on the weekends.