A driveway width of 20 feet provides enough space for two cars to pass, but not quite enough room for parking side-by-side and opening doors. If you need space for parking two cars, consider making your driveway 24 feet wide.ven if your city only allows a 14 foot opening, your driveway can widen into whatever width is necessary. For example, many homeowners opt for a driveway that begins at a single car width, but widens into a double car width near the garage.