Not if more people forego the car entirely. The marginal trip costs are high if you don't have a car. Even if you could rent one cheaply over the weekend, it's

Not if more people forego the car entirely. The marginal trip costs are high if you don't have a car. Even if you could rent one cheaply over the weekend, it's more marginal cost than if you have it in your garage. A lot of European cities with good public transport and narrow medieval roads still have less traffic than American cities with 4 lane roads.