It's a Dilemma

What to do when its 25F outside...do we ride our bikes the 3/4 mile or so to school, walk (it's a good 10 minutes longer than the old house) or drive? I have to admit I get lazy when my garage bins are frozen shut and there is enough ice on the car windows that I have to run it for 5 minutes before leaving, and drive. However, with petrol now costing us about $9/gallon I may need to rethink.