Hillman Imp

Rootes Group

Industry	Automotive
Founded	1907
Fate	Acquired by Chrysler Europe in 1967
Headquarters	United Kingdom
Products	Automobiles (including Hillman Imp)

The Hillman Imp represents a small economy automobile manufactured initially by the Rootes Group and subsequently by Chrysler Europe between 1963 and 1976. Debuting on 3 May 1963, it was notable as the first British mass-market vehicle to feature an aluminium engine block paired with an aluminium cylinder head.

Conceived by designers Michael Parkes and Tim Fry under Rootes' direction, production took place at the dedicated Linwood facility in Scotland. The Imp lineup comprised multiple variants, including the estate version known as the Husky, a van model, and a coupé, which were sold under various marques such as Sunbeam and Singer.

The Imp earned acclaim in motorsport circles, particularly with the introduction of the Rally Imp homologation model in 1964, equipped with an enlarged 998 cc engine. It achieved notable rallying success internationally, securing first and second positions at the 1965 Tulip Rally.

Despite its forward-thinking engineering, the Imp struggled with reliability problems that negatively impacted its commercial standing. These difficulties played a role in the Rootes Group’s takeover by Chrysler Europe in 1967. Production persisted until March 1976, culminating in nearly half a million units sold over a span of thirteen years.

Development

Internally designated as the APEX initiative, development of the Imp was prompted by the 1956 fuel crisis triggered by the Suez Crisis. With petrol rationing in place across the UK and declining demand for Rootes’ larger automobiles, there emerged a clear opportunity for compact, fuel-efficient vehicles. Since 1959, BMC’s Mini had already exploited this market segment. Although formally initiated in 1955, the project quickly concentrated on creating Rootes’ inaugural small car optimized for economy.

The design team led by Mike Parkes and Tim Fry was encouraged by engineering director B. B. Winter to develop a vehicle aligned with consumer requirements. Initial prototypes—such as one nicknamed "The Slug"—bore resemblance to bubble cars but were dismissed by Rootes’ styling committee, prompting a transition toward more conventional and practical design choices.

Rigorous testing occurred under severe conditions across diverse environments including Norway, East Africa, and Canada, supervised by Chief Development Engineer Ken Sharpe.

Prior attempts by Rootes to produce small cars included the pre-war Little Jim (1938–1939) and the post-war Little Jimmy prototypes from 1949; however, these earlier efforts did not directly influence the Imp’s final form.

Powering the Imp was a 742cc engine inspired by Coventry Climax’s FWMA design. Initially envisaged in three displacements—800cc, 875cc, and 998cc—the plan was scaled back due to engineering expenses, increased vehicle mass, and reliability concerns associated with the 998cc dry-liner engines. Consequently, only the 875cc variant became standardised. This meant that unlike competitors such as the Mini, the Imp offered just one engine size. An attempt to increase displacement through a taller engine block was abandoned because of cost implications and uncertain outcomes. Certain long-stroke engines were produced and subsequently bored out to 1150cc for competition use by racers including Paul Emery and Andy Dawson.

Later iterations of the 998cc engines found in Rallye Imps incorporated costly wet liners designed exclusively for motorsport tuning rather than everyday driving. The maximum dependable displacement for standard engines was established at 948cc; however, neither this nor a planned 928cc variant—intended for a Mark III Imp project cancelled due to Chrysler’s budget reductions—reached production. The concept behind the 928cc engine later reappeared in the Chrysler Sunbeam.

Mark I Imp: 1963–1965

The Hillman Imp made its debut on 2 May 1963, with the Linwood factory officially inaugurated by HRH Duke of Edinburgh. Among the earliest models, one is preserved at the Glasgow Museum of Transport, while another 1963 example is exhibited at the National Motor Museum, Beaulieu.

Prior to and following its release, the Imp garnered considerable attention from motoring journalists. In 1962, Small Car & Mini Owner drew focus to its all-aluminium, water-cooled rear-mounted engine. The Daily Express described it as "the first baby car ever built by the Rootes Group". At launch, pricing was competitive with £508 for the standard version and £532 for the deluxe model.

The designation "Imp" originated from Ailsa Craig Ltd., a marine engine firm acquired by Warsop Fram Group in 1962. Rootes Group obtained the name through a trade involving a Humber Super Snipe automobile, highlighting the vehicle’s compact size and positioning it as a direct rival to the Mini.

The Imp was equipped with a sophisticated water-cooled four-cylinder engine inspired by the Coventry Climax FWMA design, featuring an all-aluminium alloy overhead camshaft and a fully synchromesh aluminium transaxle—an impressive technical accomplishment for its era. The engine was inclined at 45° to reduce the center of gravity and enhance handling characteristics.

To mitigate typical oversteer associated with rear-engined cars, the Imp utilized a semi-trailing arm independent rear suspension—a complex and expensive solution rarely found in small cars at that time. Initially, swing axle front geometry led to understeer issues, which were later resolved by modifying camber through repositioning lower pivot points.

UK sales climbed from approximately 33,000 units in 1963 to 50,142 in 1964, but fell to 42,663 in 1965 due to reliability problems primarily caused by inadequate rear-engine cooling. This negatively impacted its market standing amid stiff competition from the Mini, which sold over 1.19 million units throughout the decade.

The Mark I was offered exclusively as a two-door saloon available in Basic and De Luxe specifications. In October 1964, Rootes launched a premium Singer Chamois variant to widen its market appeal.

Mark II Imp: 1965–1968

In response to early Mark I shortcomings, Rootes Group reintroduced the Imp featuring essential mechanical and aesthetic improvements. The Mk II replaced the pneumatic throttle linkage and automatic choke with traditional mechanisms, refined front suspension geometry, and incorporated upgraded trim. Key enhancements included adding a water pump, enlarging cylinder head ports and valves, and introducing 'Mark II' door badges.

Mark III Imp: 1968–1976

Although never officially designated as "Mark III," the Imp underwent revisions following Rootes Group’s acquisition by Chrysler Europe in 1968, resulting in the "Chrysler Imp" branding. Updates comprised redesigned instrument panels and steering wheels, substituting the large central speedometer with a horizontal set of four gauges that varied by model. A single multifunction stalk replaced the previous dual stalk controls. While these modifications aligned with industry trends toward production streamlining, some critics felt that the new dashboard missed an opportunity given the original’s well-regarded ergonomic design.

Rootes, Chrysler, and the Conclusion of Production

Early quality issues significantly damaged the Imp's market reputation, restricting sales despite its attractive pricing, distinctive design, and economical running costs. Approximately half of all units produced were manufactured within the initial three years. Reliability concerns were further compounded by maintenance difficulties related to the alloy engine and frequent failures of the Giubo coupling. In terms of popularity, the Mini consistently surpassed the Imp.

Rootes' heavy financial commitment to both the Imp and the Linwood manufacturing facility contributed to the company’s economic struggles. While labor disputes and connections with Chrysler USA were primary causes of Rootes’ financial losses, the Imp’s disappointing commercial performance also played an important role. Following Lord Rootes’ passing in 1964, Chrysler completed its acquisition of Rootes by 1967, subsequently folding it into Chrysler Europe. In 1968, retail prices for most Imp variants were reduced by over four percent despite inflation pressures in the UK. Some critics attribute the Imp’s withdrawal from production in March 1976—after fewer than 441,000 vehicles were built—to decisions made by Chrysler’s management; nevertheless, it was Chrysler Europe’s broader challenges that led to its takeover by Peugeot two years later.

The Imp enjoyed one of the longest production runs among British cars, spanning 13 years. Its replacement in Chrysler UK’s portfolio was the Chrysler Sunbeam, a three-door hatchback derived from the Hillman Avenger’s rear-wheel-drive platform. Both models continued to be assembled at Linwood until the plant ceased operations in 1981 after eighteen years. Meanwhile, assembly at Ryton persisted until December 2006 when production of the Peugeot 206 was relocated to Slovakia.

Design

Developed as a direct competitor to the BMC's Mini, the Imp employed a compact rear-engine, rear-wheel-drive configuration that maximized passenger and luggage space. Its distinctive rear hatch provided convenient access to the luggage compartment situated behind the back seat.

It holds the distinction of being Britain’s first mass-produced vehicle with a rear-mounted engine and was also pioneering in its use of a diaphragm spring clutch. The incorporation of a baulk-ring synchromesh transaxle enhanced gear shifting smoothness, addressing problems experienced by earlier Minis.

Noteworthy features included a folding rear bench seat, an automatic choke—a rarity outside North America until well into the 1970s—and instrumentation displaying temperature, voltage, and oil pressure levels, which were uncommon in small cars during that era.

The overhead camshaft engine offered flexibility and ease of tuning due to improved airflow compared to typical OHV engines. Performance upgrades were achievable through modifications such as enhanced silencers and carburettors. However, Rootes’ modifications for mass production rendered this engine less robust than its Coventry Climax predecessor.

The Imp’s power unit was based on the Climax FWMA design but was distinct from the FWMC engine employed in Lotus automobiles.

Marketing

Initially promoted by Rootes as a premium second family car featuring high-end specifications, the Imp’s market positioning gradually shifted toward emphasizing exceptional fuel economy. It incorporated certain cost-saving design choices reminiscent of Eastern European manufacturers such as Škoda and Lada, targeting consumers seeking an affordable economy vehicle. For a period, the basic Hillman Imp held the title of Britain’s most inexpensive new car, temporarily stimulating sales growth.

Variants and Badge Engineering

During the Imp's production span from 1963 to 1976, Rootes and later Chrysler UK developed four distinct body styles. The initial saloon featured an innovative rear window that opened to serve as a hatchback, complemented by a foldable rear seat—an uncommon feature for compact cars of that era. In 1965, a van variant named the "Commer Imp" was introduced. By 1967, the lineup expanded with the coupe model known as the Imp Californian, launched concurrently with an estate version called the Hillman Husky, which utilized van-based bodywork. Production of both estate and van models ceased by 1970.

To enhance market appeal amid disappointing sales figures that fell short of the target of 100,000 units annually, several badge-engineered versions were launched. These included the upscale Singer Chamois starting in 1964 and the sportier Sunbeam Sport from 1966, both featuring twin-carburettor engines. Export markets often saw Singer models sold under the Sunbeam name until Chrysler phased out the Singer brand in 1970. In certain countries such as France, "Sunbeam" was used as the brand for all British Rootes vehicles, including the Imp and Husky.

The coupe body featured a more sharply angled windscreen and a fixed rear window. Although it debuted with a sporty design at the 1967 Paris Motor Show as the Sunbeam Stiletto, it did not deliver improvements in acceleration or top speed compared to the saloon, which had slightly superior aerodynamics. 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 introduction of the Imp marked a major and expensive undertaking for Rootes, which had limited recent experience with small car manufacturing despite having offered the compact Hillman Minx back in 1931. By the time of the Imp’s release, the Minx had grown into a medium-sized family vehicle. Rootes was among the pioneers in mass-producing an aluminium engine, a sophisticated process that necessitated establishing a new computerised assembly facility in Linwood, Renfrewshire. This development was supported by UK Government Regional Assistance funding aimed at creating approximately 6,000 jobs in an area impacted by shipbuilding industry decline along the River Clyde.

The investment encompassed a state-of-the-art die-casting plant dedicated to aluminium engine blocks and a shareholding in a new Pressed Steel Company plant responsible for producing body panels. However, Linwood’s location—over from Rootes’ primary Ryton factory—posed logistical complications. Engine castings were transported to Ryton for machining and assembly before being returned to Linwood for final installation, resulting in a round trip managed through a complex rail timetable coordinating parts and finished goods movement. To streamline logistics further, Linwood also manufactured body pressings for the Hillman Avenger, which were then shipped south to Ryton.

The workforce recruited locally mainly came from shipbuilding backgrounds and lacked specialized automotive assembly expertise, which affected build quality and reliability of the Imp. Additionally, frequent industrial disputes and strikes contributed to production challenges. Approximately half of the total production of around 500,000 Imps occurred within the first three years.

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 about 1964 until 1970 when Imp production ended to focus on the Hillman Avenger. Todd Motors maintained two final assembly lines at Petone shared between Avenger and Hunter models alongside Chrysler Valiant production.

In Australia, Rootes Australia assembled Imps at its Port Melbourne plant beginning in 1964. The following models were produced:

• PM Imp: Offered only in standard trim from 1964 to 1965; constructed from UK Mk I CKD kits. A Super Imp version was introduced in 1965 incorporating upgrades that influenced subsequent IMP II models.
• PA Imp ("IMP II"): Available in standard or Super trim between February 1966 and March 1968; continued to rely on UK Mk I kits.
• PB Imp ("IMP III"): Produced from 1968 until approximately 1970 with standard or Super trims; initially utilized UK Mk I kits before transitioning to UK Mk II kits and engines. The last units may have exclusively used CKD Imp Sport body shells.
• Hillman GT: Assembled from Sunbeam Imp Sport CKD kits between 1967 and 1968.
• Hillman Sonic/Stiletto: A convertible model manufactured by Eiffel Tower Motors in Dandenong for Chrysler Australia.

Variants

• Hillman Imp Mark I (1963–1965)
• Hillman Imp de Luxe Mark I and II (1963–1968)
• 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) available as coupé and fastback saloon
• Hillman Husky (1967–1970), estate model
• Commer Imp Van (1965–1968)
• Hillman Imp Van (1968–1970)
• Hillman Imp Caledonian (1975–1976), a limited edition (~2,000 units) in Cherry Red with additional accessories, offered in Super and De Luxe trims
• Singer Chamois Mark I and II (1964–1970)
• Singer Chamois Rallye (1965–1968), rally-spec version featuring luxury appointments and a 998cc engine
• Singer Chamois Sport and Coupé (1967–1970)
• Sunbeam Imp Sport (1966–1970)
• Sunbeam Sport (1970–1976)
• Sunbeam Chamois (export markets outside the UK)
• Sunbeam Stiletto (1967–1972)
• Sunbeam Californian
• Sunbeam Imp Basic and De Luxe Mark I and II (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) accomplished a coast-to-coast endurance challenge across the United States, sanctioned by American Rodding Magazine. Covering 3,011 miles from New York City to Los Angeles in 48 hours, 9 minutes, and 54 seconds, it surpassed the previous "world record" set by Erwin George “Cannonball” Baker in 1933, maintaining an average speed of 63.7 mph.

The Imp gained considerable acclaim in rallying when Rosemary Smith triumphed at the 1965 Tulip Rally. This success led Rootes Group to introduce a dedicated rally conversion under both Hillman and Singer badges called the Imp Rallye. Although it faced a contentious disqualification in 1966 after winning the Coupe des Dames, the model demonstrated strong performance in touring car competitions. Bill McGovern clinched three consecutive British Saloon Car Championship titles from 1970 to 1972 driving the Bevan-prepared Sunbeam Imp with modest factory backing.

Within UK club racing scenes, multiple Imp variants excelled in the sub-1000 cc Special Saloon division, driven by competitors such as Ian Forrest and Gerry Birrell. Even today, Imps actively participate in historic rally events across the UK, frequently securing podium positions in championships like the HRCR Clubmans Rally Championship.

Globally, the Imp also achieved recognition in Asian saloon car contests throughout the 1980s with drivers including Andrew Bryson and Pardaman Singh. The 998 cc engine was further adapted for three-wheeled sidecar racing during the 1970s and 1980s, often equipped with custom exhaust systems and Twin Weber carburetors. Several sidecar teams competed at the Isle of Man TT races; notably, Roy Hanks finished eleventh in the 1976 TT 1000cc Sidecar category. Sidecar outfits powered by Imp engines continue to be competitive within classic racing circuits.

In hydroplane competition, Andy Chesman secured the World Hydroplane championship title in 1972 utilizing a modified Imp engine. Following his acquisition of Greetham Engineering, Chesman engineered a wedge-shaped cylinder head that enhanced the original 998 cc unit to produce 125 bhp with twin Weber carburetors and increased displacement to 1220 cc. During the BP-sponsored Windermere records week in October 1972, he raised the R1 Class water speed record to 89 mph. Chesman retained this record until his passing in a powerboat accident in 1998.

Additional resources

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

External links

• The Hillman Imp story
• The Imp Club official site
• Information on the Hillman Imp and its badge-engineered variants
• Andy’s Hillman Imp homepage — an extensive source focused on Hillman Imps and their engine derivatives
• How Margaret Thatcher’s policies contributed to the Linwood plant closure — article marking the 50th anniversary and shutdown of the Linwood assembly facility