The 1928 Grand Prix season saw the Monegasque driver Louis Chiron, and his Bugatti, take seven Grand Prix victories. For 1928, the AIACR abandoned its 1.5-litre formula. Manufacturer interest was low, not helped by the increasing economic downturn. Instead cars would have to be between 550 and 750 kg to an open engine-formula. Originally, the World Manufacturers' Championship was planned on seven national races but as the year went on, five were cancelled and only the Indianapolis 500 and Italian Grand Prix were held. Falling under the mandatory races, the whole championship was cancelled. With the epic win for Bentley in the 1927 Le Mans and the success of the inaugural Mille Miglia road-race grabbing the public's attention, more races turned to sports- and touring-car racing.