Development
Known internally within the Rootes Groups as the APEX project, the Imp came about because of the fuel shortage caused by the Suez Crisis in 1956. Petrol was rationed in the UK, sales of the heavy cars for which Rootes was known had dramatically slumped, and there was a huge market for small economical cars with low fuel usage. The BMC's Mini had already taken advantage of the opportunity, with production starting in 1959. Although the project officially began in 1955, the market for small cars was soon recognised and it was evident that the project would evolve into Rootes' first small, economical car.
Seeing an opportunity, Mike Parkes and Tim Fry offered to design the car: "Well, Mike Parkes and I were very good friends. So we went to the director of engineering, B. B. Winter, and said to him we could design you just the car we want. And he said: 'Alright, get on with it then!'".[9] The early stages of development presented "The Slug", which had clear similarities to a bubble car. However, the Rootes design board were not satisfied with this approach, and ordered the design team to press forward. That led to the next stage of the Slug, which appeared more utilitarian with appropriate styling.
Extensive road testing was carried out in Norway in winter conditions, East Africa summer weather 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. The first being the 1938–1939 Little Jim prototype, which featured a conventional front-engined rear-wheel drive layout equipped with a 750 cc water-cooled engine[12][13] followed later by the post-war rear-engined 1949 Little Jimmy prototype by Craig Miller that would make use of a Volkswagen-based twin-cylinder engine.[14]
It was originally envisaged by Rootes the 742 cc Coventry Climax FWMA inspired engine would be available in three sizes, 800 cc, 875 cc and 998 cc. However it was not to be as through a combination of engineering production costs, Apex’s increased weight and size, together with experimental dry-liner 998 cc engines being unreliable, resulted in only the 875 cc engine being standardized at the cost of imposing a constraint on the Imp as a one-capacity car that competitors like the Mini did not experience. One alternative solution considered before being dropped was to develop a new taller block giving the engine a longer stroke whilst retaining the 875 cc engine's dry-liners, however this would have been an expensive procedure and would have only been worth the investment had the Imp been a success. 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 1150 cc[15] and used to great in effect in competition by the likes of Paul Emery, Andy Dawson, Ian Carter and others.
The later 998 cc engines in the Rallye Imps meanwhile would on the other hand make use of expensive wet-liners and were not really intended for road use, rather only for competition and further tuning. It was later discovered the largest reliable limit the 875 cc engine would tolerate was 948 cc, however in the absence of more development neither the 948 cc engine nor the envisaged 928 cc engine were used, the latter originally being proposed as early as the mid-1960s for a projected Mark III Imp that became a victim of Chrysler’s cost-cutting[16] before it reappeared years later in the Chrysler Sunbeam.
Mark I Imp: 1963–1965
The Hillman Imp was officially announced on 2 May 1963, when HRH Duke of Edinburgh was invited to open the factory in Linwood.[17] After the opening, he then drove a silver Imp to Glasgow Airport. One of the first Imps produced is currently on display at the Glasgow Museum of Transport. Another early example from 1963 is at the National Motor Museum, Beaulieu, with the registration 1400 SC.
Before and after its announcement, the Imp garnered significant attention from the motoring press. In 1962, the Small Car & Mini Owner magazine published an article titled "Enter the AJAX!", particularly noting the all-aluminium water-cooled rear engine.[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".[19] In June 1963, the Motor Sport magazine commented on the press' reaction to the Imp who strongly favoured the Imp in terms of its engine, gearbox and competitive price; at launch, the standard model cost £508 1s 3d, while the deluxe version was £532 4s 7d.[20]
Mark II Imp: 1965–1968
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.
The Mk I Imps had a pneumatic throttle linkage and an automatic choke, both of which were replaced by more conventional items on the Mk II. The Mk II also had improved front suspension geometry, and several trim and detail changes. Although the car was constantly improved over its production life, there was no single change as significant as those in 1965. 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.[27]
Mark III Imp: 1968–1976
The Imp was never officially badged nor referred to as the "Mark III". However, changes were made to the range when the Rootes Group was fully acquired by Chrysler Europe, and so that version is sometimes referred to as the "Chrysler Imp".
After Rootes Group's acquisition by Chrysler in 1968, the entire range was revised, except for the Stiletto. The instrument panel and steering wheel were redesigned. 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. The right-hand dial, the speedometer, was now to one side of the driver's normal sightline, while one multi-functional stalk on the right side of the steering column replaced the two control stalks that had been directly behind the steering wheel, one on each side. 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". The more modern arrangement on the Imp was seen by some as a missed opportunity.[28]
Rootes, Chrysler and end of production
The initial problems damaged the Imp's reputation and popularity trailed off, with half of all production being from the first three years. 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. Regular failures of the Giubo couplings also occurred. It was overshadowed in popularity by the Mini.
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. The Imp's commercial failure added to the major losses suffered by Rootes, although the main reasons for these losses were unresolved industrial unrest and the effects of the link with the Chrysler Corporation of the USA. The link was initiated by Lord (William) Rootes in 1964 as a partnership, but he died in October of that year and by 1967 the company had been acquired by Chrysler, to become part of Chrysler Europe. A year later, ahead of the 1968 London Motor Show, the recommended retail prices of most Imp models were reduced for the domestic market by more than four per cent,[29] despite the general price inflation affecting the UK.
