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 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.
The season is remembered primarily for a deadly accident at the Italian Grand Prix. The Talbot of Emilio Materassi swerved off the road at 200 km/h, rolled a number of times and crashed into the crowd, killing Materassi and 22 other people. The accident was the greatest single loss of life in motor-racing history to that time, and still the second worst to date, after the 1955 Le Mans disaster.
With the open formula, the Bugatti Type 35, and its variants was the dominant car. Talbot, Maserati and Alfa Romeo all had some success, but it was Bugattis that filled the entry-lists across Europe. Albert Divo won the Targa Florio for Bugatti's fourth successive year, after a well-prepared challenge from female Czech driver Eliška Junková. A month earlier, top Italian driver Pietro Bordino was killed in practice for the Alessandria Circuit. The rounds of the Italian Drivers Championship attracted many of the best drivers. A close contest developed between Chiron and Nuvolari (both Bugatti), Materassi (Talbot) and Campari (Alfa Romeo), with Campari taking the title. In the United States, the Indianapolis 500 was won by rookie Louis Meyer in a Miller. He went on to be crowned the season's AAA Champion.