> cars _save_ _time_
Cars only save time if there aren't very many of them. Look at Northern Virginia, at 3 A.M you can drive 10 miles in 10 minutes because the roads are direct and have high speed limits, but that same drive would take close to an hour during the day.
Car commutes are shorter than transit commutes in well-designed cities.
But even otherwise, you don't need a dedicated full-time driver.