After serving his apprenticeship with
De Dion-Bouton,
Clément and
Panhard et Levasseur he left France to work in England in 1900. After a short time with the Crowden Motor Car Company he joined
Humber Limited in 1901 and was to become their chief engineer. He designed their 8-10 and 10-12 models. They were highly successful but their design was, unusually for Coatalen, totally conventional. In 1906 aged 26 or 27 he went into partnership with bicycle manufacturer
William Hillman. In 1908 he drove their
Hillman-Coatalen car in the
Isle of Man Tourist Trophy race.
Sunbeam 12-16 His first design was one of the outstanding light car designs of its day. In 1912 three 12-16s took the first three places in Dieppe's ''Coupe de l'Auto'' 2-day race for 3-litre cars. The first of the three cars was also third in the race for Grand Prix cars. But his designs rapidly became less innovative and he seemed to copy Peugeot developments rather than use his own. Sunbeam produced a greater variety of aero engines than any other business during the war. W O Bentley said this was "in part because Coatalen was so good at selling ideas to the Admiralty and War Office." He was later put in charge of the technical and designing staffs of all S.T.D. subsidiaries.
Race cars With the success of 1.5-litre Talbot-Darracq cars, his main interest became racing cars. Their wins catapulted Sunbeam to the highest echelons of international competition from the legendary success at the 1912 Coupe de l’Auto to winning the 1914 and
1922 Tourist Trophy and 1923 and 1924 Grand Prix. Coatelen collaborated with the industry foremost designer Ernest Henry on the
1922 Grand Prix Sunbeams and had some of the most respected drivers of the period –
Henry Segrave,
Jean Chassagne and
Kenelm Lee Guinness driving his Sunbeam cars. In 1926, Sunbeam's racing activities were taken into the S.T.D. company and moved to
Suresnes near Paris in France and although Coatalen continued working part-time in Wolverhampton, he spent most of his time in Paris. On his direction, Sunbeam was among the first British manufacturers to provide front wheel brakes.
Record breaking Sunbeam became heavily involved in land speed record attempts including the successful
1000HP car of 1927 and the failed '' '
Silver Bullet' '' of 1930. Louis Coatalen designed the engines for the first car to exceed 150 miles per hour and the first car to exceed 200 miles an hour, the 1000 horsepower Sunbeam driven by
Henry Segrave. ==France==