Not necessarily - if gridlock is too bad then owning a car isn't worthwhile. In theory, an auction system and good planning ought to keep permit levels at the

Not necessarily - if gridlock is too bad then owning a car isn't worthwhile. In theory, an auction system and good planning ought to keep permit levels at the point where selling another permit would push down the value of all the permits to a a net loss. In practice, it's going to be a lot clumsier than that (say, take last year's number and add 3%), but auctions and long-term planning can still rein in sales.