Sunbeam Chamois

Rootes Group

Industry	Automotive
Founded	1900s
Fate	Taken over by Chrysler Europe in 1967
Successor	Chrysler Europe
Headquarters	United Kingdom

The Hillman Imp is a compact economy car that was manufactured by the Rootes Group and subsequently by Chrysler Europe from 1963 until 1976. Introduced on 3 May 1963, it was notable for being the first British mass-produced vehicle to feature an aluminium engine block and cylinder head.

Conceived by Michael Parkes and Tim Fry under Rootes' direction, the Imp was assembled at the dedicated Linwood factory in Scotland. The model lineup extended beyond the standard saloon, including estate versions (known as the Hillman Husky), vans, and coupés.

The Imp gained moderate recognition in club-level and international rally competitions. In 1964, Rootes launched a homologation special called the Rally Imp, equipped with a larger 998 cc engine. Among its significant accomplishments were first and second places overall at the 1965 Tulip Rally, achieved by factory drivers Rosemary Smith and "Tiny" Lewis.

Although it introduced several innovations, the Imp struggled with reliability problems that ultimately tarnished its reputation in the marketplace. These difficulties played a role in Rootes Group’s takeover by Chrysler Europe in 1967. Production persisted until March 1976, with nearly half a million units produced over its thirteen-year run.

Development

Internally designated as the APEX project at Rootes, the Imp was conceived as a response to the fuel crisis triggered by the 1956 Suez Crisis, which led to petrol rationing across the UK and caused a slump in sales of Rootes’ traditionally heavier automobiles. Identifying an expanding demand for small, fuel-efficient cars—already capitalized on by BMC’s Mini debuting in 1959—Rootes initiated development in 1955 to create their inaugural compact model.

The design team, led by engineers Mike Parkes and Tim Fry, initially produced "The Slug," a prototype inspired by bubble cars. However, this design was rejected by Rootes’ board in favor of a more practical alternative. Rigorous testing under harsh conditions—including Scandinavian winters and Arctic climates in Canada—was overseen by Chief Development Engineer Ken Sharpe and his team.

Previous Rootes small car efforts included prototypes such as the Little Jim (1938–1939) and the rear-engined Little Jimmy (1949), though these had minimal impact on the Imp’s final development.

Rootes originally intended to offer engines inspired by Coventry Climax FWMA designs in multiple sizes: 742cc, 800cc, 875cc, and 998cc. Nevertheless, escalating engineering expenses, increased vehicle mass, and reliability concerns with experimental dry-liner 998cc engines resulted in only the 875cc version being standardized. This decision meant that unlike rivals such as the Mini, the Imp was limited to a single engine displacement. Proposals for a taller engine block to extend stroke were dismissed due to cost considerations and uncertain market acceptance. Some long-stroke engines were produced and later bored out to 1150cc for racing purposes by competitors like Paul Emery and Andy Dawson.

Later Rallye Imp variants employed 998cc wet-liner engines that were expensive to produce and primarily intended for motorsport rather than everyday use. Although it was demonstrated that the 875cc engine could be reliably enlarged to 948cc, neither this nor a planned 928cc engine—intended for a Mark III Imp model abandoned after Chrysler’s cost reductions—were ever manufactured. The concept of the 928cc engine eventually reappeared years later in the Chrysler Sunbeam.

Mark I Imp: 1963–1965

The Hillman Imp was officially introduced on 2 May 1963, with the Linwood factory inaugurated by HRH Duke of Edinburgh. Early examples are preserved in the Glasgow Museum of Transport and the National Motor Museum, Beaulieu. Prior to and following its debut, the Imp garnered considerable media interest, lauded for its all-aluminium, water-cooled rear engine and attractive pricing—standard versions were priced at £508, with deluxe models at £532.

The designation "Imp" originated from Ailsa Craig Ltd., a marine engine manufacturer acquired by Warsop Fram Group in 1962. This name was exchanged with Rootes Group in return for a Humber Super Snipe vehicle, aiming to highlight the car’s compact size and position it as a rival to the Mini.

Equipped with an advanced water-cooled four-cylinder aluminium overhead camshaft engine, inspired by the Coventry Climax FWMA design, the Imp also featured a fully synchromesh aluminium transaxle—a pioneering setup at that time. The engine was tilted at a 45° angle to lower the centre of gravity, enhancing handling characteristics.

To counteract the common oversteer found in rear-engine vehicles, the Imp utilized a semi-trailing arm independent rear suspension—a sophisticated approach rarely seen in small cars during that era—after thorough evaluation of swing-axle systems like those used in the Chevrolet Corvair. Its front suspension initially employed swing axle geometry but was later adjusted to mitigate understeer.

Sales in the UK climbed from approximately 33,000 units in 1963 to 50,142 in 1964 but dropped to 42,663 in 1965 due to reliability concerns related to insufficient engine cooling. This undermined the vehicle’s reputation and challenged Rootes Group’s ambition to compete against the Mini, which achieved sales exceeding 1.19 million during that period.

The Mark I was available as a two-door saloon offered in Basic and De Luxe specifications; a premium Singer Chamois variant was introduced in October 1964.

Mark II Imp: 1965–1968

Following early difficulties with the Mark I, Rootes Group reintroduced the Imp featuring significant mechanical and aesthetic enhancements. The Mk II replaced the pneumatic throttle linkage and automatic choke with conventional mechanisms, refined front suspension geometry, and updated trim levels. Key improvements included adding a water pump, enlarging cylinder head ports and valves, alongside 'Mark II' door badges.

Mark III Imp: 1968–1976

Although never formally designated "Mark III," the Imp underwent updates after Rootes Group was acquired by Chrysler Europe in 1968; it is sometimes referred to as the "Chrysler Imp." Changes encompassed redesigned instrument panels and steering wheels, substituting the large central speedometer with a horizontal layout of four circular gauges. Controls were consolidated onto a single stalk mounted on the steering column. While intended to modernize the dashboard design, some critics viewed this as a missed chance compared to previous ergonomic strengths.

Rootes, Chrysler and end of production

Initial reliability difficulties damaged the Imp’s market standing, leading to falling sales despite its competitive price point, unique styling, and economical running costs. Misunderstandings regarding maintenance of alloy engines and frequent failures of Giubo couplings further harmed perceptions of dependability. The Imp was eclipsed by rivals such as the Mini.

Rootes’ substantial financial commitment to both the Imp and Linwood factory contributed to its economic struggles. Although industrial disputes and connections with Chrysler USA were major influences, poor commercial performance of the Imp intensified losses. After Lord Rootes passed away in 1964, Chrysler completed its takeover of Rootes by 1967, creating Chrysler Europe. In 1968, most Imp variants saw price cuts despite inflationary pressures in the UK.

Responsibility for discontinuing the Imp in March 1976—after fewer than 441,000 units were built—is often attributed to Chrysler’s management. Chrysler Europe itself faced difficulties and was absorbed by Peugeot two years later. The Imp enjoyed a notable production span of thirteen years but was replaced within Chrysler UK’s lineup by the rear-wheel-drive Chrysler Sunbeam hatchback launched in 1977. Both models continued production at Linwood until its closure in 1981.

Meanwhile, the Ryton facility remained operational until December 2006 when Peugeot relocated manufacture of the Peugeot 206 to Slovakia.

Design

Developed to rival the BMC's Mini, the Imp utilized a compact rear-mounted engine combined with rear-wheel-drive to optimize space for both passengers and luggage. A distinctive feature was its rear hatch that opened to allow loading through the backrest of the rear seat.

This model was the first British mass-produced vehicle to incorporate a rear engine and pioneered the use of a diaphragm spring clutch. Its transaxle, equipped with baulk-ring synchromesh, enhanced gear shifting reliability, overcoming difficulties encountered by early Minis.

Among its forward-thinking elements were a foldable rear bench seat, an automatic choke—a feature uncommon outside the United States until the 1970s—and instrumentation that included gauges for temperature, voltage, and oil pressure, in contrast to the warning lights that had largely replaced such meters since the 1950s.

The overhead camshaft configuration provided superior airflow compared to traditional OHV engines and allowed straightforward tuning for enhanced power through upgraded silencers and carburettors. Nevertheless, Rootes' modifications for large-scale production rendered the engine less robust than its Coventry Climax predecessor.

The Imp's powerplant was derived from the Climax FWMA engine, differing from the FWMC unit found in Lotus vehicles.

Marketing

Rootes initially marketed the Imp as an upscale second vehicle tailored for well-to-do families, highlighting its superior build quality and advanced technology. Subsequently, their strategy shifted toward positioning it as an ultra-economical option featuring cost-saving design modifications, aiming to compete with affordable Eastern European brands such as Škoda and Lada. At one stage, the Hillman Imp held the distinction of being Britain's least expensive new car, which temporarily stimulated sales.

Variants and "badge engineering"

Throughout its production lifespan, Rootes—and later Chrysler UK—offered four distinct body configurations. The original saloon (1963–1976) included a rear window that opened to facilitate easier access to luggage behind the fold-down rear seat—a feature uncommon among small cars at that time. The "Commer Imp" van was introduced in 1965. In 1967, a coupe version called the Imp Californian debuted alongside an estate model named the Hillman Husky, which was based on van bodywork. Although estate prototypes featuring extended saloon roofs were developed, they never reached the market. Production of both van and estate variants ceased in 1970.

To increase market appeal amid disappointing sales figures—falling short of the intended 100,000 units per year—several badge-engineered versions were launched: the upscale Singer Chamois (from October 1964) and the sportier Sunbeam Sport (from October 1966), both equipped with twin-carburettor engines. Singer models were sold as Sunbeams in many export markets until Chrysler UK discontinued the Singer brand in May 1970. In countries like France, all British Rootes models including the Imp and Husky were marketed under the "Sunbeam" name.

The coupe shared many design elements with the saloon but featured a more gently sloped windscreen and a fixed rear window. Although it made its debut at the Paris Motor Show in October 1967 as part of the Sunbeam Stiletto lineup with a sporty look, it did not provide any performance improvement over the standard saloon, which actually had slightly better aerodynamic qualities. The coupe also appeared in less powerful versions as the Hillman Imp Californian (introduced January 1967) and as a premium Singer Chamois coupe.

Manufacture

The Imp marked a major and expensive venture for Rootes, a company with limited recent experience in manufacturing small cars, despite having introduced the compact Hillman Minx back in 1931. By the time the Imp debuted, the Minx had transitioned into a mid-sized family vehicle. Rootes broke new ground by implementing an aluminium engine in mass production for the Imp, a process more intricate than simply substituting cast-iron engines. To facilitate this innovation, Rootes established a new, computerized assembly facility in Linwood, near Paisley. This development was partially financed through UK Government Regional Assistance grants aimed at generating roughly 6,000 jobs in a region suffering from shipbuilding industry downturns along the River Clyde. The investment encompassed a sophisticated die-casting plant dedicated to aluminium engine blocks and included participation in a new Pressed Steel Company plant responsible for producing body panels.

Nevertheless, Linwood's geographical position introduced logistical difficulties. Engine castings produced there were transported approximately 300 miles to Rootes' principal factory at Ryton-on-Dunsmore for machining and assembly before being sent back for final assembly—resulting in a 600-mile total journey. This process relied on intricate railway timetables coordinating the movement of parts and completed vehicles between the two sites. To offset transportation expenses, body panels for the Hillman Avenger were also manufactured at Linwood and shipped south to Ryton. This operational structure remained throughout the entire production period of the Linwood-built Imp.

The local labor force, mostly drawn from shipbuilding backgrounds, lacked specialized skills necessary for automobile assembly, which negatively influenced the Imp’s build quality and dependability. Additionally, industrial relations challenges, including frequent strikes during the 1960s and 1970s, further disrupted manufacturing.

Approximately half a million Imps were produced overall, with about half of these completed within the initial three years.

Overseas assembly

Complete knock down (CKD) kits were shipped abroad for assembly in countries such as Australia, Costa Rica, Ireland, Malaysia, Malta, New Zealand, Philippines, Portugal, South Africa, Uruguay, and Venezuela. In New Zealand, Todd Motors assembled Imps under the Hillman brand from around 1964 until production ended in 1970 to focus on the Hillman Avenger. Todd Motors operated two final assembly lines at Petone: one shared by the Avenger and Hunter, and another dedicated to Chrysler Valiant models.

In Australia, Rootes Australia assembled Imps at their Port Melbourne facility starting in 1964. The lineup included:

• PM Imp: Offered only in standard trim; manufactured from 1964 to 1965 using UK Mk I CKD kits. A Super Imp variant was introduced in 1965 featuring upgrades that were incorporated into subsequent models.
• PA Imp ("IMP II"): Available in standard or Super trims; sold between February 1966 and March 1968; based on UK Mk I CKD kits.
• PB Imp ("IMP III"): Produced from 1968 until approximately 1970; initially assembled from UK Mk I CKD kits before transitioning to Mk II kits and engines.
• Hillman GT: Constructed from Sunbeam Imp Sport CKD kits; produced between 1967 and 1968.
• Hillman Sonic/Stiletto: A convertible model manufactured by Eiffel Tower Motors of Dandenong for Chrysler Australia.

These variants demonstrated ongoing product enhancements tailored specifically to meet local market demands throughout their production span.

Variants

• Hillman Imp Mark I (1963–1965)
• Hillman Imp de Luxe Mark I and II (1963–68)
• Hillman Super Imp (1965–1974)
• Hillman Imp (1968–1976)
• Hillman GT (1967–?), developed by Chrysler Australia based on the Singer Chamois Sport; never officially marketed as "Hillman Imp GT"
• Hillman Imp Californian (1967–1970), available in coupé and fastback saloon styles
• Hillman Husky (1967–1970), estate variant
• Commer Imp Van (1965–1968)
• Hillman Imp Van (1968–1970)
• Hillman Imp Caledonian (1975–1976), a limited run of approximately 2,000 units in Cherry Red featuring additional accessories, offered in Super and De Luxe trims
• Singer Chamois Mark I & II (1964–1970)
• Singer Chamois Rallye (1965–68), a rally-spec model with enhanced features and a 998cc engine
• Singer Chamois Sport and Coupé (1967–1970)
• Sunbeam Imp Sport (1966–1970)
• Sunbeam Sport (1970–1976)
• Sunbeam Chamois, sold in export markets outside the UK
• Sunbeam Stiletto (1967–1972)
• Sunbeam Californian
• Sunbeam Imp Basic and De Luxe Mark I & II for the North American market

Cars using Imp mechanicals

• Beach Mk4
• Bond 875 and its variants
• BS Nymph
• Clan Crusader
• Concept Centaur GT
• Davrian
• Ginetta Cars G15
• Siva Llama

In August 1964, between the 12th and 14th, the Sunbeam Imp sports sedan (registration ZT-86-20) undertook an officially sanctioned US coast-to-coast endurance run by American Rodding Magazine. This feat surpassed the previous "world record" set by Erwin George “Cannonball” Baker in 1933. Covering 3,011 miles from New York City to Los Angeles, the Imp completed the journey in 48 hours, 9 minutes, and 54 seconds, maintaining an average speed of 63.7 mph.

The Imp gained considerable acclaim in rallying after Rosemary Smith secured victory at the 1965 Tulip Rally. This success led Rootes Group to manufacture a rally-specific conversion under both the Hillman and Singer brands named the Imp Rallye. Although it faced a contentious disqualification in 1966 following a win in the Coupe des Dames, the model excelled in touring car competitions. Bill McGovern piloted the Bevan-prepared Sunbeam Imp to three consecutive British Saloon Car Championship victories from 1970 through 1972, despite minimal factory involvement.

Within UK club racing circuits, various Imp models dominated the Special Saloon category for engines under 1000 cc. Prominent racers such as Ian Forrest, Harry Simpson, Ricky Gauld, John Homewood, Roger Nathan, Gerry Birrell, Ray Payne, and Chris Barter contributed to this dominance. Today, Imps remain active contenders in historic events like the HRCR Clubmans Rally Championship.

Globally, particularly in Asia during the 1980s, the Imp achieved success in saloon car racing thanks to drivers including Andrew Bryson and Pardaman Singh. The 998 cc engine was also adapted for competitive use in three-wheeled racing sidecars throughout the 1970s and 1980s, frequently fitted with Twin Weber twin-choke carburetors. Multiple sidecar teams powered by Imp engines competed at the Isle of Man TT races; Roy Hanks attained the highest finish of eleventh place in the 1976 TT 1000cc Sidecar event. These powerplants continue to be competitive within classic sidecar racing circles.

Andy Chesman utilized the Imp engine to claim the World Hydroplane championship title in 1972. After acquiring Greetham Engineering, a specialist firm, he engineered a wedge-shaped cylinder head that boosted engine output to 125 bhp at 998 cc. He further increased displacement to 1220 cc by employing longer cylinder liners. In October 1972 at Windermere, Chesman set an R1 Class water speed record of 89 mph—a record he maintained until his fatal powerboat accident in 1998.

Additional resources

• Morgan, Tim (May 2017). Hillman Imp: The Essential Buyers Guide. Veloce Publishing.

External links

• The history behind the Imp
• The Imp Club official site
• Information on the Hillman Imp and its badge-engineered variants
• Andy's Hillman Imp homepage — dedicated to Hillman Imps and their engine derivatives
• The impact of Margaret Thatcher's policies on the Linwood factory closure — article marking the 50th anniversary and plant shutdown