Quite possibly. Someone noticed that the actual speed of traffic in London is always 9 miles per hour. If traffic improves, more people drive until it gets down to 9 mph. If traffic gets worse, people decide driving is too much trouble and traffic improves to 9 mph :)

Likely but by that time we probably wont care because we would be able to sign up for a car online, tell it how many occupants, have it pick us up automatically, join on to other vehicles to form car trains on the roads for optimal efficiency, join mesh networks with neighboring vehicles to organize traffic, never have to stop for signs/lights because cars would seemlessly inter-weave through intersections, all while everyone texts safely.