A sleeper (US English) or Q-car (British English) is a car that has high performance and an unassuming exterior. Sleeper cars are so called because their exterior looks similar or identical to a standard or economy-class car. In some cases the car appears worse due to seeming neglect on the owner's part, typically referred to as "all go and no show". While appearing to be a standard or neglected car, internally they are modified to have higher performance levels. The American nomenclature comes from the term sleeper agent, while the British term derives from the Q-ships used by the Royal Navy. In the February 1963 Motor Sport magazine editor Bill Boddy said "the modifications carried out by Lotus have turned the Lotus Cortina into a 'Q' car par excellence". The British film The Long Arm (1956; aka The Third Key) mentions a Q-car (unmarked) patrolling the city by night, indicating that the term was in use among UK law enforcement at least a decade earlier. In July 1964, British magazine Motorcycle Mechanics carried an announcement from editor Bill Lawless of the use of two unmarked police "Q-cars" – a black Daimler SP250 sports car and a green Austin A40 Farina – patrolling the A20 road between London and Maidstone, Kent. Beginnings in the West The Chrysler 300 letter series began in 1955 with the Chrysler C-300. With a 331 in3 (5.4 L) FirePower V8, the engine was the first in a production passenger car to be rated at , and was by a comfortable margin the most powerful in American cars of the time. By 1957, with the 300C, power was up to . These cars were among the first sleepers, marketed as high-end luxury cars from the traditional luxury marque Chrysler, but with a high-end homologation racing engine. However, these cars lose their "sleeper value" due to both their rarity (this series was highly luxurious; it was made in limited numbers and examples are very expensive), and the well publicized successes of Carl Kiekhaefer in NASCAR racing (1955–1956); though the model is an important precursor of the muscle car. The 1968 Mercedes-Benz 300SEL 6.3 was a powerful sedan with a subdued exterior. A trend of overtly powerful saloon cars with subtle body modifications is exemplified by the work of Mercedes-AMG and Brabus on unassuming Mercedes saloons. The 1986 Lancia Thema 8.32, fitted with a Ferrari V8 engine, has been