Founded the Renault company in 1899 with his brothers, Fernand and Marcel. Responsible for design and manufacturing, Louis took control in 1908 after Fernand retired. Marcel was killed in the Paris-Madrid race in 1903. During the war, Renault was put under the control of the Germans and Louis chose to remain. When France was liberated he was arrested for collaboration and died in questionable circumstances while awaiting trial.
The youngest of five children born into a Paris bourgeoisie family, Renault was fascinated by engineering and mechanics from a very early age, and would spend many hours in the Serpollet steam car workshop or tinkering with old Panhard engines in the tool shed of the family's second home in Billancourt.
He built his first car in 1898, a modified De Dion-Bouton cycle which featured a revolutionary universally jointed propeller driveshaft that included a three speed gearbox plus a reverse, with the third gear in direct drive (Louis was to patent this idea a year later). On 24 December 1898, he won a bet with his friends that his invention was capable of driving up the slope of Lepic street in Montmartre. As well as winning the bet, Renault received 12 definite orders for the vehicle. Seeing the commercial potential in his ingenuity, he teamed up with his two elder brothers Marcel (1872-1903) and Fernand (1865-1909) who had business experience from assisting in the running of their father's textiles firm, to form the Renault Frères company in 1899.
Initially, business and administration was handled entirely by the elder brothers, with Louis dedicating himself to design and manufacturing. However, in 1908 he took overall control of the company after Fernand retired for health reasons (Marcel having being killed earlier in the Paris-Madrid motor race of 1903).
Over the next forty years Renault was to remain very controlling of his company, dealing with Renault's rapid expansion and various cases of labor unrest while designing countless new inventions, most of which are still in use today, such as hydraulic shock absorbers, the modern drum brake, compressed gas ignition, the turbocharger, and the taximeter.
He was decorated with the Legion of Honor after the First World War for the success of his military designs, that most famously included the revolutionary Renault FT-17 tank.
During the Nazi occupation of France during the Second World War, the Renault company (like all French companies) was put under the total control of the Germans, and Louis chose to remain. Consequently, when France was liberated in 1944, he was arrested for industrial collaboration with Nazi Germany, and died under what some call questionable circumstances, while awaiting trial in Fresnes Prison.