The Leyton House CG911 was a Formula One racing car designed by Chris Murphy and Gustav Brunner for the 1991 Formula One season. Unlike its CG901 predecessor, which used a Judd EV V8 engine, the CG911 used an Ilmor 2175A V10 engine. Leyton House Racing initially started the 1991 season with Maurício Gugelmin and Ivan Capelli as their drivers, as they had in 1990, but Karl Wendlinger replaced Capelli for the final two races of the season. For 1992, when Leyton House renamed themselves as March F1, the CG911 was updated to the March CG911B specification, with Wendlinger, Jan Lammers, Paul Belmondo and Emanuele Naspetti all sharing driving duties. Although March initially intended to run the CG911C in 1993 with Lammers and Jean-Marc Gounon, the team folded and they did not compete that year.

The 1991 FIA Formula One World Championship was the 45th season of FIA Formula One motor racing and the 42nd season of the Formula One World Championship. It featured the 1991 Formula One World Championship for Drivers and the 1991 Formula One World Championship for Constructors, which were contested concurrently over a sixteen-race series that commenced on 10 March and ended on 3 November.