Notable successes for this model include the 1965 Tulip Rally in which the works Imps of Rosemary Smith and "Tiny" Lewis finished first and second overall.

Considered ahead of its time,[8] the Imp nevertheless suffered from reliability problems, which harmed its reputation and led to the Rootes Group being taken over by Chrysler Europe in 1967.

Extensive road testing was carried out in Norway in winter conditions, East Africa in the height of summer and in Arctic conditions in Canada by a small team led by Ken Sharpe (Chief Development Engineer, Ryton)[10][11] Rootes did previously look at building a small car twice, even if both ultimately contributed little to the development of the Imp.

A few long-stroke engines were built and evaluated, the work not completely going to waste as they would go on many years later to be bored out up to 1150cc[15] and used to great in effect in competition by the likes of Paul Emery, Andy Dawson, Ian Carter and others.

[18] The same year, the Daily Express published an article titled "It's the new 'baby'", calling it "the first baby car ever built by the Rootes Group".

The water-cooled four-cylinder power unit was inspired by the Coventry Climax FWMA engine, featuring an all-aluminium alloy overhead camshaft, combined with a full-synchromesh aluminium transaxle.

[24] To attain balanced handling, the Imp actually used swing axle geometry at the front, but that initially led to too much understeer, and the camber was later reduced by lowering the pivot points.

Reliability problems had quickly surfaced, mainly due to poor cooling of the rear engine, and the public image of the car was becoming negative.

Following the initial problems that affected the Mark I, the Rootes Group decided to re-introduce the Imp with significant changes both mechanically and cosmetically.

Among the changes were an added water pump, cylinder head with larger ports and valves, and 'Mark II' emblems on the side of the doors.

[28] The large speedometer previously positioned behind the steering wheel was replaced by a horizontal row of four circular dials/displays of varying detail and complexity, according to the model involved.

[28] The earlier Imp had been praised for the good ergonomic quality of its dash-board/fascia, and its replacement reflected similar trends in other new and modified UK vehicles at a time of "production rationalization".

It still sold thanks to its competitive price, distinctive styling, and cheap running costs, but sales never lived up to expectations for what had become a very competent small car.

Another problem that contributed to the reputation for poor reliability was the lack of understanding of the maintenance needs of alloy engines by owners and the motor trade in the 1960s.

The company's huge investment in both the Imp and the Linwood production plant was to be a significant part of the demise of the Rootes Group.

Being a direct competitor to the BMC's Mini, it used a space-saving rear-engine, rear-wheel-drive layout to allow as much luggage and passenger capacity as possible in both the rear and the front of the car.

The baulk-ring synchromesh unit for the transaxle compensated for the speeds of gear and shaft before engagement, from which the Mini had suffered during its early production years.

Among them were a folding rear bench seat, automatic choke which was rare on compact cars outside the United States until the 1970s, and gauges for temperature, voltage and oil pressure which have been largely omitted since the 1950s in favour of emergency lights.

Useful improvements in power could be gained by replacing the standard silencer (muffler) with one that impeded the exhaust gas flow less and with better carburettors.

However, in adapting the design to suit modern mass-production methods, Rootes had left the engine more fragile than the Coventry Climax model from which it had been derived.

At one point the basic Hillman Imp was the cheapest new car on the British market, which increased low sales figures for a time.

A coupe, the Imp Californian, was introduced in 1967 at the same time as the van's pressings were used to create an estate car, badged "Hillman Husky".

The new body style made its first appearance at the Paris Motor Show in October 1967, with the introduction of the sporting Sunbeam Stiletto.

The UK Government Regional Assistance policy provided financial grants to the Rootes Group to bring approximately 6,000 jobs to the area.

To aid with balancing the logistical costs of this operation, body pressings for the Hillman Avenger were also made at Linwood, but transported south to Ryton on the component trains.

[citation needed] The local West of Scotland workforce, recruited mainly from the shipbuilding industry, did not bring the distinct skills necessary for motor vehicle assembly, and Imp build quality and reliability suffered accordingly.

Unassembled cars were exported for assembly in Australia,[3] Costa Rica,[3] Ireland,[3] Malaysia,[3] Malta,[3] New Zealand,[3] Philippines,[3] Portugal,[3] South Africa,[3] Uruguay,[3] and Venezuela.

The following models were produced:[33] Between August 12 and 14, 1964, a Sunbeam Imp sports sedan (ZT-86-20) completed the First American Rodding Magazine sanctioned endurance run and broke a world record in the process, previously set by Erwin George “Cannonball” Baker in 1933,[42] driving from New York City, to Los Angeles, California, covering 3,011 miles in 48 hours, 9 minutes, 54 seconds at an average speed of 63.7 mph.

Notable exponents of the Imp in racing include Ian Forrest, Harry Simpson, Ricky Gauld, John Homewood, Roger Nathan, Gerry Birrell, Ray Payne and Chris Barter.

The Imp was also successfully raced and rallied in other parts of the world, notably Asia, where drivers including Andrew Bryson and Pardaman Singh regularly won saloon car categories into the 1980s.