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Sunbeam Imp

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Adapted from the English Wikipedia article Sunbeam Imp, available under CC BY-SA 4.0Updated 10 August 2025
Hillman Imp
Company typeAutomobile model
IndustryAutomotive
PredecessorNone
FoundedMay 3, 1963; 63 years ago (1963-05-03)
FounderRootes Group
DefunctMarch 1976 (1976-03)
FateDiscontinued
SuccessorChrysler Sunbeam
Headquarters
Linwood, Scotland
,
United Kingdom
Area served
United Kingdom, Europe
ParentRootes Group, Chrysler Europe

The Hillman Imp was a compact economy automobile manufactured by the Rootes Group and subsequently by Chrysler Europe between 1963 and 1976. Introduced on 3 May 1963, it marked a milestone as the first British mass-produced vehicle featuring an aluminium engine block combined with an aluminium cylinder head.

Conceived by Michael Parkes and Tim Fry under Rootes’ direction, the Imp was assembled at the Linwood facility in Scotland. The model lineup expanded to include multiple variations such as the estate version known as the Hillman Husky, a commercial van, and a sporty coupé.

The Imp experienced moderate achievements in both club-level and international rally competitions. In 1964, Rootes launched a homologation special named the Rally Imp, equipped with an enlarged 998 cc power unit. This variant earned significant rallying accolades, including securing first and second positions at the 1965 Tulip Rally.

Although regarded as technologically advanced during its era, the Imp’s reliability shortcomings adversely affected its reputation, which in turn played a role in Rootes Group’s takeover by Chrysler Europe in 1967. Production persisted until March 1976, with total sales approaching half a million units over its 13-year lifespan.

Development

Internally designated as the APEX initiative within Rootes Group, the Imp project originated as a reaction to the fuel shortages caused by the 1956 Suez Crisis. This event drastically diminished demand for Rootes’ larger automobiles while simultaneously creating a market for smaller, fuel-efficient cars. The BMC Mini had already established dominance in this segment since 1959. Initiated in 1955, the project quickly concentrated on delivering Rootes’ inaugural small economy vehicle.

Design engineers Mike Parkes and Tim Fry proposed designing a car specifically addressing this emerging market niche, gaining endorsement from engineering director B. B. Winter. Early prototypes such as "The Slug" resembled microcars but were ultimately rejected by Rootes’ styling committee, prompting a redesign towards more conventional aesthetics.

Comprehensive testing covered diverse environments—from Norway’s harsh winters to East Africa’s heat and Arctic conditions in Canada—under the supervision of Chief Development Engineer Ken Sharpe.

Prior to the Imp, Rootes had experimented with small car concepts including the 1938–1939 Little Jim prototype featuring a front-engine, rear-wheel-drive layout powered by a 750cc engine, and the post-war 1949 rear-engined Little Jimmy prototype utilizing a Volkswagen-based powertrain; however, these earlier efforts had minimal influence on the Imp’s development.

The Imp utilized a 742cc engine inspired by the Coventry Climax FWMA design, originally intended to be offered in three displacements: 800cc, 875cc, and 998cc. Due to escalating engineering expenses, increased vehicle mass, and reliability issues with experimental dry-liner 998cc engines, only the 875cc variant was standardized. This resulted in the Imp having a single engine option, unlike competitors such as the Mini which offered multiple sizes. Alternative approaches like creating a taller engine block for extended stroke were evaluated but dismissed because of cost concerns and uncertain market reception. Some long-stroke engines were produced and later bored out to 1150cc for racing purposes by drivers including Paul Emery and Andy Dawson.

Subsequent Rallye Imp models employed expensive wet liner 998cc engines designed primarily for motorsport rather than everyday driving. Testing indicated that reliable displacement for the standard 875cc engine could be increased up to approximately 948cc; however, neither this nor a proposed 928cc engine—intended for a Mark III Imp—were brought into production due to Chrysler’s cost-cutting strategies. The concept of the 928cc engine was eventually revived in the Chrysler Sunbeam model.

Mark I Imp: 1963–1965

The Hillman Imp debuted on 2 May 1963, with the official opening of the Linwood factory conducted by HRH Duke of Edinburgh. Following the ceremony, he drove a silver Imp to Glasgow Airport. Early examples of this model are now displayed at the Glasgow Museum of Transport and the National Motor Museum, Beaulieu. The Imp garnered considerable media interest both before and after its release. In 1962, Small Car & Mini Owner spotlighted its all-aluminium, water-cooled rear engine, while the Daily Express described it as "the first baby car ever built by the Rootes Group." Pricing at launch was competitive, with the standard version costing £508 and the deluxe £532.

The name "Imp" originated from Ailsa Craig Ltd., a marine engine manufacturer acquired by Warsop Fram Group in 1962. Rootes Group secured the rights to this name through a trade involving a Humber Super Snipe vehicle. This branding underscored the car’s compact dimensions as a direct competitor to the Mini.

The Imp was equipped with an innovative water-cooled four-cylinder aluminium overhead camshaft engine, inspired by the Coventry Climax FWMA design, coupled with a fully synchromesh aluminium transaxle—an advanced feature considered technically demanding at that time. The engine was installed at a 45° angle to reduce the center of gravity and enhance handling performance.

To counteract the common oversteer tendency of rear-engined vehicles, engineers incorporated a semi-trailing arm independent rear suspension—an advanced solution rarely found in small cars then. The front suspension utilized modified swing axle geometry to mitigate early understeer issues. These engineering choices were intended to improve driving dynamics relative to competitors.

In the UK market, sales climbed from around 33,000 units in 1963 to more than 50,000 in 1964 but then fell to about 42,600 in 1965 due to reliability concerns associated with rear-engine cooling problems. This decline affected buyer confidence amid fierce competition from the Mini, which sold over 1.1 million units during that decade. The Mark I was available as a two-door saloon in Basic and De Luxe trims, with a premium Singer Chamois variant introduced in October 1964.

Mark II Imp: 1965–1968

In response to shortcomings identified in the Mark I, Rootes Group reissued the Imp featuring notable mechanical and aesthetic improvements. The Mk II replaced the pneumatic throttle linkage and automatic choke with more conventional mechanisms and refined front suspension geometry. Significant upgrades included adding a water pump, enlarging cylinder head ports and valves, and introducing 'Mark II' door badges. These modifications represented the most extensive revision throughout its production run.

Mark III Imp: 1968–1976

Although never officially designated "Mark III," the model range underwent revisions following Rootes Group’s acquisition by Chrysler Europe in 1968—often referred to as the "Chrysler Imp." Updates encompassed redesigned instrument panels and steering wheels, replacing the large central speedometer with a horizontal array of four round gauges customized by trim level. Control stalks were streamlined into a single multifunction stalk positioned on the right side of the steering column. While these changes aligned with efforts toward production efficiency, some critics considered them a lost chance to build upon the earlier model’s well-regarded ergonomic dashboard design.

Rootes, Chrysler, and the Conclusion of Production

Early reliability issues significantly harmed the Imp's reputation, restricting sales despite its attractive pricing, distinctive design, and economical running costs. Approximately half of all units were produced within the initial three years. Problems with maintaining the alloy engine and frequent failures of the Giubo coupling further damaged its market perception. The Mini remained more popular throughout its production.

The large investment Rootes made in both the Imp and the Linwood manufacturing facility played a role in the company’s financial struggles. Although industrial disputes and connections with Chrysler USA were major contributors to Rootes’ losses, the Imp’s disappointing commercial results added to these challenges. Following Lord William Rootes' initiation of a collaboration with Chrysler in 1964, Chrysler had fully acquired Rootes by 1967, integrating it into Chrysler Europe. Despite inflationary pressures in the UK, prices for most Imp variants were lowered in 1968.

Responsibility for the Imp’s discontinuation in March 1976—after fewer than 441,000 units were produced—is frequently attributed to Chrysler’s management. The wider Chrysler Europe operation faced difficulties and was eventually taken over by Peugeot two years later. Over its 13-year lifespan, the Imp became one of Britain’s longest-produced vehicles. Its UK successor was the Chrysler Sunbeam, a three-door hatchback built on the rear-wheel-drive Hillman Avenger platform. Both models continued production at Linwood until the plant shut down in 1981 after 18 years.

Meanwhile, the Ryton assembly plant remained operational until December 2006 before Peugeot shifted production of the 206 model to Slovakia.

Design

Developed as a direct rival to BMC’s Mini, the Imp utilized a compact rear-engine, rear-wheel-drive configuration to optimize luggage and passenger space at both ends of the vehicle. It featured an innovative rear hatch that opened to allow access to luggage stored behind the rear seats.

It was notable as the first British mass-produced car with a rear-mounted engine and also pioneered the use of a diaphragm spring clutch. The baulk-ring synchromesh transaxle was designed to equalize gear and shaft speeds prior to engagement, resolving early transmission problems experienced by the Mini.

Distinctive design elements included a folding rear bench seat, an automatic choke—which was uncommon in small cars outside North America until the 1970s—and instrumentation displaying temperature, voltage, and oil pressure readings rather than relying solely on warning lights as had been common since the 1950s.

The overhead camshaft engine offered flexibility and ease of tuning, providing superior airflow compared to conventional OHV engines. Performance enhancements could be achieved by replacing the standard silencer with one that reduced exhaust flow restrictions and by upgrading carburettors. However, Rootes’ modifications for mass production rendered the engine less robust than its Coventry Climax predecessor.

The Imp’s powerplant was derived from the Climax FWMA engine series, whereas Lotus employed an FWMC variant featuring a distinct cylinder head design.

Marketing

Initially, Rootes marketed the Imp as a potential second vehicle for well-to-do families—a groundbreaking small car boasting high quality and above-average features. Later marketing efforts shifted toward positioning it as an ultra-economical model incorporating some cost-saving design compromises reminiscent of Eastern European economy cars such as Škoda and later Lada. At one stage, the basic Hillman Imp held the distinction of being Britain’s least expensive new car, which temporarily stimulated sales.

Variants and Badge Engineering

During the Imp's production run, Rootes (which later became Chrysler UK) developed four distinct body styles. The initial saloon model (1963–1976) included a rear window hatch that opened, facilitating easier access to the cargo area behind the fold-down rear seat—a feature uncommon in small vehicles at that time. In 1965, a van version named the "Commer Imp" was introduced. Two years later, in 1967, the coupe variant called the Imp Californian was launched alongside an estate car marketed as the "Hillman Husky," which utilized van body panels and sported a unique design. Production of both the van and estate ceased by 1970.

To increase sales and reach the target of 100,000 units annually, Rootes introduced badge-engineered models such as the more upscale Singer Chamois from 1964 and the sportier Sunbeam Sport starting in 1966, equipped with twin-carburettor engines. In many export markets, Singer models were sold under the Sunbeam name even before Chrysler UK discontinued the Singer brand in 1970. In countries like France, all Rootes British vehicles—including the Imp and Husky—were branded as Sunbeam.

The coupe shared much of its design with the standard model but featured a windscreen with a shallower rake and a fixed rear window. Although it debuted with a sportier appearance at the 1967 Paris Motor Show alongside the Sunbeam Stiletto, it did not offer improved acceleration or higher top speeds; aerodynamic advantages were actually in favor of the regular saloon. This coupe style was also applied to less powerful versions like the Hillman Imp Californian and to luxury variants such as the Singer Chamois.

Manufacture

The Imp represented a major financial undertaking for Rootes, which had limited recent experience producing small cars despite having originally introduced the compact Hillman Minx back in 1931. By the time of the Imp’s debut, the Minx had transitioned into a mid-size family vehicle. Rootes broke new ground by employing an aluminium engine in mass production for the Imp—a process far more involved than simply substituting cast-iron components. To facilitate this, Rootes established a new computerised assembly facility in Linwood, near Paisley, benefiting from UK Government Regional Assistance grants intended to generate approximately 6,000 jobs in an area struggling with shipbuilding industry decline.

This investment included a state-of-the-art die-casting plant dedicated to aluminium engine blocks and involved acquiring a shareholding in a new Pressed Steel Company plant manufacturing body panels. However, Linwood’s remote location created logistical difficulties: engine castings were transported about 300 miles to Rootes’ Ryton-on-Dunsmore factory for machining and assembly before being shipped back another 300 miles to Linwood for final installation—resulting in a round trip of roughly 600 miles. This complicated transportation was coordinated through an intricate rail timetable balancing parts and finished vehicles between locations. To improve efficiency, Linwood also produced body pressings for the Hillman Avenger, which were then sent south to Ryton.

The workforce at Linwood mainly consisted of former shipyard employees who lacked specialized automotive assembly experience, which contributed to challenges with build quality and reliability of the Imp. Production was further hindered by frequent industrial disputes and strikes that were prevalent across British manufacturing sectors during the 1960s and 1970s.

In total, around half a million Imps were manufactured, with approximately fifty percent of these produced within the first three years of production.

Overseas assembly

Complete knock down (CKD) kits were shipped abroad for assembly in countries including Australia, Costa Rica, Ireland, Malaysia, Malta, New Zealand, Philippines, Portugal, South Africa, Uruguay, and Venezuela. In New Zealand, Todd Motors assembled Hillman vehicles from approximately 1964 until 1970. Production of the Imp ceased to focus on the Hillman Avenger, which was prioritized on the limited assembly lines shared with the Hunter and Chrysler Valiant models.

In Australia, Rootes assembled Imps at their Port Melbourne facility beginning in 1964, manufacturing several variants:

  • PM Imp: Offered only in Standard trim (1964–65), constructed from UK Mk I CKD kits. The Super Imp was introduced in 1965, incorporating enhancements that were carried forward into subsequent versions.
  • PA Imp ("IMP II"): Available in Standard or Super trims (1966–68), still utilizing UK Mk I CKD kits.
  • PB Imp ("IMP III"): Offered in Standard or Super trims (1968–circa 1970), initially based on Mk I kits but later produced from Mk II kits; some late models featured Mk II engines and Sport bodywork.
  • Hillman GT: Manufactured from Sunbeam Imp Sport CKD kits between 1967 and 1968.
  • Hillman Sonic/Stiletto: A convertible model built by Eiffel Tower Motors of Dandenong for Chrysler Australia.

These models demonstrated continuous adjustments to meet local market preferences and manufacturing capacities.

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 designated as "Hillman Imp GT"
  • Hillman Imp Californian (1967–1970) coupé and fastback saloon
  • Hillman Husky (1967–1970) estate variant
  • Commer Imp Van (1965–1968)
  • Hillman Imp Van (1968–1970)
  • Hillman Imp Caledonian (1975–1976), a limited edition (~2,000 units) finished in Cherry Red with added features, offered in Super and De Luxe trims
  • Singer Chamois Mark I and II (1964–1970)
  • Singer Chamois Rallye (1965–68), a rally conversion featuring luxury equipment and a 998cc engine
  • Singer Chamois Sport and Coupé (1967–1970)
  • Sunbeam Imp Sport (1966–1970)
  • Sunbeam Sport (1970–1976)
  • Sunbeam Chamois (export-only model)
  • Sunbeam Stiletto (1967–1972)
  • Sunbeam Californian
  • Sunbeam Imp Basic and De Luxe Mark I and II (for North American market)

Cars using Imp mechanicals

From August 12 to 14, 1964, the Sunbeam Imp sports sedan (registration ZT-86-20) undertook an officially sanctioned US coast-to-coast endurance run organized by American Rodding Magazine, breaking a "world record" previously held by Erwin George “Cannonball” Baker since 1933. The journey spanned 3,011 miles along newly constructed Interstate Highways from New York City to Los Angeles in 48 hours, 9 minutes, and 54 seconds, averaging a speed of 63.7 mph.

The Imp earned a notable motorsport reputation after Rosemary Smith's victory at the Tulip Rally in 1965. This achievement prompted Rootes Group to develop a dedicated rally version marketed under both Hillman and Singer badges as the Imp Rallye. Although it faced a contentious disqualification following the Coupe des Dames victory in 1966, the Imp excelled in touring car competitions with Bill McGovern securing three consecutive British Saloon Car Championship titles in 1970, 1971, and 1972.

Privateer outfit George Bevan also dominated early-1970s British Saloon Car Championships with limited factory backing. Within UK club racing circuits, various Imp configurations flourished in under-1000 cc Special Saloon classes, driven by notable racers such as Ian Forrest and Gerry Birrell. The Imp continues to participate actively in historic rally events across the UK, sustaining its legacy.

Globally, the Imp saw success in Asian saloon car racing through drivers like Andrew Bryson and Pardaman Singh during the 1980s. Its 998 cc engine powered three-wheeled racing sidecars throughout the 1970s and 1980s, often modified with Twin Weber carburetors. Several teams competed with Imp-powered sidecars at the Isle of Man TT races; Roy Hanks achieved the best result by finishing eleventh in the 1976 TT 1000cc Sidecar race. The engine remains competitive within classic sidecar racing circles.

In hydroplane competition, Andy Chesman claimed the World Hydroplane championship title in 1972 using an Imp engine. After acquiring Greetham Engineering—specialists in Imps—he enhanced the engine to deliver 125 bhp with twin Weber carburetors and increased displacement to 1220 cc. During Windermere’s BP-sponsored records week in October 1972, Chesman set a new R1 Class water speed record of 89 mph. He maintained this record until his passing in 1998.

Additional resources

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

External links

Related profiles

HHillman ImpSSinger ChamoisSSunbeam ChamoisSSunbeam Sport
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