In the Washington, DC area they have what they call slug lots. You stand in line at a metro lot and people pull up and will be going to the State Department, Pentagon or WhiteHouse, somewhere governmenty. If you don't have three people in the car, you cannot use the HOV lanes (High Occupancy Vehicles) and are relegated to those people who would rather be alone.

So yes!! We really do carpool here! :) And its free. (oh, the government pays our gas!)

!tip