The Société des Pétroles Jupiter, Shell's French agents, provided three standard fuel options: Gasoline, Benzole and a 70/30 blend of the two. Teams were allowed to add up to 2% by volume of their own additives. As before, all liquids (fuel, oil and water) could only be replenished after every 20 laps (). Night-time, when headlights had to be used, was defined by the ACO for the race as between 9.30pm and 4am. Entries In the middle of the Great Depression, the auto-industry was being hit very hard. Only 33 cars entered for the race, of which only 19 arrived. That said it was a quality field with two big Bentley entries challenged by a mighty 7-litre supercharged Mercedes and one of the supercharged Alfa Romeos dominating European racing, both privately entered. France could muster only two works Tractas, a BNC and a privateer Bugatti to their premier touring car race. Note: The first number is the number of entries, the second the number who started. Defending champions Bentley once again arrived with a solid works team, this year bringing a trio of their big Speed Six model. Introduced in 1928 as a competitor to the Rolls-Royce Phantom I, it had a 6.6-litre engine that produced 190 bhp giving it a top speed of 185 kp/h (115 mph). Company director (and race winner in 1928 and 1929), Woolf Barnato would drive the lead car – the same chassis that had been entered in the 1929 race. This year his co-driver was his wealthy friend Glen Kidston. The other two were driven by 1924-winner Frank Clement with former Stutz-driver Dick Watney, and 1927-winner and journalist Sammy Davis with Clive Dunfee. Back in 1928, Barnato's fellow race-winner, Sir Henry “Tim” Birkin had seen the threat posed by the new supercharged Mercedes and Alfa Romeos to Bentley's dominance of touring car racing. He had approached W. O. Bentley and Barnato about supercharging the green cars. Barnato was not convinced and W.O loathed the idea. He eventually found an investor in the form of young heiress, and keen motorist, Dorothy Paget (who already owned a Mercedes-Benz SSK). The cars were not race-ready in time for the 1929 race; however Barnato quietly approved sufficient funds to allow the required production quantity to be met. Based on the 4½ Litre model, a massive, distinctive Roots supercharger was fitted in front of the radiator. This boosted the