I noticed today that the only time I make a point of sharing a transportation experience via social media is when I drive a car. At least twice now I have posted updates on Twitter (I really can’t bring myself to say I “tweeted”) about using a Zipcar. And for good reason. Zipcar is a magical program where, with the wave of a card over a windshield, I unlock a car — and so far, a different car each time — find the keys inside, and drive off. To paraphrase their motto, I use a car when I want to. […]