What if you time a short errand door to door? Something like going to the post office. Really, by the time you add up all the mini-tasks involved with driving to somewhere w/in a mile or two, it takes less actual time to do it by bike. And it's more scenic, makes your butt cuter, etc .

Driving entails: open garage door, put on seat belt, insert key, start car, back out, close garage, wait to enter street, drive time, time looking for a parking spot, park, turn off car, remove seat belt, exit car, lock car, walk across parking lot.

Biking entails: open garage, hop on bike that has combo lock already on it, ride to destination, roll up to the front door, lock bike to rack. Rinse, repeat.