Sharing driverless cars with up to five people per trip increased total vehicle mileage by only a quarter. Better still was a fleet of driverless taxis that get people to and from high-capacity fixed guideway transit hubs; when shared driverless cars were teamed with about one in four travelers using rail transit, vehicle miles increased only marginally rather than doubling with solo cars and no rail transit. Models of a mixture of driverless and traditional human driven car traffic were shown to increase the number of cars on the road during peak travel as well as increase overall car mileage in all but one scenario: traditional cars and shared driverless cars and working in conjunction with high-capacity fixed guideway transit.