You make an excellent point. A single person (even one with low energy useage) can't compete against larger groups of people living together and driving together.

OTOH a hypermiler can make it to the midpoint of your survey, easily.

The problem with carpools is that you are generally driving more miles to pick up people who are out of the way from your normal commuting route, and having to depend on everyone to have their act together or face being late for work....