The Bristol Type 450 was a successful sports car racing prototype model, designed in 1953 by Bristol Cars and based on the abortive ERA G-type Formula Two car of 1952. Although most sources state that only three 450s were built, photographic evidence suggests that at least four were in existence at one point in time. The cars were constructed specifically to contest the prestigious 24 Hours of Le Mans endurance race, at which they won both their class and the team prize in both 1954 and 1955. In addition to its race victories, the Bristol 450 also took a number of outright speed records for the 2-litre class during trials at the Montlhéry circuit in 1953. Following the 1955 Le Mans disaster, which killed Pierre Levegh and 83 spectators, Bristol withdrew from direct involvement in motorsport and all but one of the 450s were broken up.

The fundamental design of the Bristol 450 was laid down by Robert Eberan von Eberhorst, and completed by his protégé and successor David Hodkin, as the chassis for the ERA G-type Formula 2 car, Leslie Johnson's attempt to resuscitate the ERA name in 1952. The G-type was initially planned to run using a custom built ERA engine, but when funding became a problem the design was adapted to incorporate the popular Bristol straight-6 engine, also used with some success by Cooper, Frazer Nash and AC. However, engine modifications made by Hodkin resulted in engine failure in all three of the G-type's Grand Prix outings, despite being driven by rising star Stirling Moss. At the end of the 1952 season, out of money and in failing health, Johnson sold the project to the car manufacturing arm of the Bristol Aeroplane Company.

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