The second-generation Forfour is jointly developed with Renault. "Motor Trend" reported the second-generation Forfour shares approximately 70% of its parts with the third generation Renault Twingo. Smart CEO Annette Winkler has reported that the W453 will retain the second Generation Fortwo trademark hemispherical steel safety cell, marketed as the "Tridion" cell. The Fortwo will continue to be assembled at Smartville, and the Forfour will be manufactured alongside the Renault Twingo 3 in Novo Mesto, Slovenia. Smartville, where the W450 and W451 build series have been manufactured, underwent a 200 million euro upgrade beginning in mid-2013, in preparation for the C453 Fortwo. The new Forfour, along with the new Fortwo went on sale in October, shortly after their public reveals at the Paris Motor Show.