Bike to everything day

A friend of mine works from home one day a week. He decided that on this day he would use his bike instead of the car. If he needs to step out for lunch or errands he will leave the car at home. This is an interesting idea. What if we pick a day of the week designated as a bike only day? Barring emergencies, anything we need to do that day will be done on our bikes. After all 40% of urban travel is 2 miles or less.