You can mount every Thule roof box on Thule crossbars as long as legal requirements are followed. We don't make specific recommendations when it comes to the ideal roofbox dimensions for your car, but we do recommend to consider your transport requirements, such as special dimensions and amount of luggage. You will find on our website, thule.com, a wide selection of designs, sizes, colours and features available within the Thule roof box assortment.