 In 1905 Guglielmo's grandsons, Vittorio and Pietro Diatto, began Diatto-Clément, a cooperative venture making motor-vehicles under license from French manufacturer Clément-Bayard owned by industrialist Adolphe Clément-Bayard.By 1909 they had full ownership of 'Autocostruzioni Diatto' and began developing their own motor-vehicles and exporting them worldwide.From 1905 the company built two and four cylinder cars based on the Clément-Bayard, a leading contemporary French manufacturer.