(first posted 1/31/2016) Europe has had many great rear engined cars, some more appealing than others. It still has one, the Porsche 911, which is perhaps one of the most accomplished cars on the market now or ever. Britain, however, has had only one; it had its flaws, some fairly reported, some exaggerated in many accounts. But the Imp project in many ways tells a significant part of the post war British motor industry and post war industrial story on its own.
In 1955, the Rootes Group was making a steady living producing technically conservative but style conscious cars, such as the Hillman Minx, Sunbeam Rapier and Humber Hawk to a market centered on Great Britain, the British Commonwealth and some sales in North America. But it unarguably lacked a smaller car and a truly small car. The smallest Rootes product, the Minx, competed at a size above the Morris Minor and Ford Prefect/Anglia.
BMC had the smaller Austin A35, and there was an increasing market penetration by the truly compact cars, like the Fiat 500, and the bubble cars, like the BMW Isetta. Rootes were determined to compete at this lower point in the market, as the anticipated increase in overall volume would help Rootes to grow and be able to defend itself in any forthcoming amalgamation in the British industry.
So, in 1955, Rootes started work on what became the Imp. Actually, the initial proposal came from two young engineers – Tim Fry and Mike Parkes Fry and Parkes took their proposal for a small car to Rootes’ Engineering Director, Bernard “BB” Winter, who allowed them to create the first prototypes.
Expected production and component costs had ruled out front wheel drive, and the packaging benefits led the choice of the compact rear engine/rear drive layout. The first prototype used a Citroen 2CV engine at the rear, which was quickly replaced by a 600cc twin cylinder, hemi-head air-cooled Villiers motor cycle engin, still mounted at the rear. The resulting concept was perhaps closer to the Fiat Nuova 500 than anything else, and was known internally as the Slug, for obvious reasons.
When the Slug was presented to the Rootes brothers, they turned their noses up at the idea, and at the proposed style of the car, and requested a significant rethink. Rootes wanted a four cylinder, four adult car, with at least some of the usual Rootes style. Fry and Parkes (seen above with the car) now had their direction and Project Apex was underway.
Rootes was a never a cash rich company, so with a new car, a new engine and a new factory to fund, looking for partners was an obvious thing to do. Conscious also that a larger cast iron engine mounted at the rear would bring weight and handling penalties, Fry contacted a surprising source.
In 1950, the UK Ministry of Defence had specified a new lightweight engine for fire pumps, and the selected design came from the Coventry Climax company, a builder of engines for fork lift trucks and other industrial uses. The first version, known as FW (for feather weight) was a 1020cc, four cylinder engine built in alloy, with wedge-shaped combustion chambers and an overhead camshaft, which produced 38bhp and met the weight requirements set.
Coventry Climax recognised that motor racing was a market opportunity and also an image builder for the company, and the FWA (feather weight automotive) variant was developed. Soon, a 1097cc version was winning races, and attracting some impressive attention. Colin Chapman’s Lotus company chose a 1216cc version of the FWM (for marine) variant for the first Lotus Elite in 1957.
Rootes adapted the FWM with Coventry Climax to create the FWMA (A for automotive or Apex), with a capacity of 875cc, installing the engine with the in-line transmission and radiator in the space allocated in the Slug for its original air-cooled twin. The in-line transmission had already been designed, so a transverse installation was not possible, and Fry wanted to use the space above the engine for luggage, rather than a radiator. A front radiator was rejected because of the production and materials cost. The installation was accomplished with the engine lying at 45 degrees on the right hand side of the car and the radiator with a large fan on the left.
Among the changes made to the Coventry Climax design was to move to die casting in aluminium alloy, a first for the British industry, from sand cast iron for the block, for reduced weight, and the use of cast iron cylinder liners.
The engine had a three main bearing crankshaft, a water pump combined with the cooling fan and a chain driven overhead camshaft. Amongst the issues encountered during the development were providing adequate cooling in the rear mounted location (many rear mounted engines are air cooled for a reason), porosity in the castings, excessive oil consumption and identifying a suitable head gasket material.
The gearbox was specifically designed for the Apex, and, somewhat unusually for 1963, had synchromesh on all four speeds. It was also cast in light alloy, and was almost always praised for the quality of the gearshift and choice of ratios. Given that the engine gave peak power of 38 bhp at 5000 rpm and could rev to 7,000 rpm, 50 mph was possible in second gear, and Rootes’ performance figures could be seen as conservative.
The fuel tank was under the floor of the front boot and the filler on the closure panel for the front bonnet (hood). The spare wheel couldn’t have been further forward, helping with weight distribution.
Suspension was by straightforward swinging arms at the front with coil struts, and trailing wishbones and coil springs at the rear. The first Slug concepts cars had a swing axle rear suspension but Fry and Parkes were also well aware of the limitations of a swing axle rear suspension, and the combination of trailing wishbone rear suspension and lightweight engine effectively limited any tendency to oversteer. Indeed, some accounts suggest a swing axle rear suspension was being considered until the development team crashed a Corvair.
One issue, on the first series of cars, was that the ride height had to be raised by an inch at a late stage, so that the headlights were high enough to meet legal requirements. The resulting increased positive camber led to increased understeer, and a visually unfortunate stance on the road, which was not addressed until revisions to the suspension mountings were made in 1967.
Rootes further complicated things for themselves by using such ideas as a pneumatic throttle and an automatic choke, and the engine still had a tendency to overheat, leading to gasket failures, warped cylinder heads and huge reputational damage to the Imp. Assuming the pneumatic throttle and automatic choke had been persuaded to let the car start…..
The Imp was styled in house at Rootes, and is normally credited to Bob Saward. Saward, who joined from Ford in 1958, accepts that the Corvair was an influence, at least below the glasshouse which itself has some resemblance to the first 1962 Ford Cortina, but it was a shape that moved on clearly into the 1960s rather than looked back to the 1950s, and was the first Rootes car for many years to show no Loewy influences.
Slowly, the roofline was improved and the familiar style of the Imp emerged and by the summer of 1960 it was very close to the final production version.
Its big thing was the back window, which opened, almost hatchback style to access a sizeable rear luggage area, which could be increased by folding the rear seat back down as well, in addition to the front boot, which contained the spare wheel. Luggage volume was around 9 cu ft in front and rear compartments, increasing if the rear seats were dropped.
The interior design was perhaps even better than the exterior, helped by the large window area. The instruments were dominated by the strip speedometer in a contemporary pod, and indicators, headlight flasher and main beam were controlled by stalks beside the wheel.
Size and capacity wise, the Imp was 18 inches longer than a Mini, on a wheelbase 2 inches longer, and 5 inches wider, at 60 inches. In terms of accommodation for passengers and their belongings, the Imp was definitely ahead of the Mini. The Imp was of a similar width to the VW Beetle or the later Renault 8, but around 20 inches shorter in length and 12 inches shorter in wheelbase than the VW or Renault. Its closest rivals in size and layout from Europe were probably the SIMCA 1000 and NSU Prinz 1000, though these too were slightly larger. So, still a small car, though not a very small car, and with a power to weight ratio and measured performance very close the Mini 850 and Mini 1000, and ahead of the smaller Fiat 600. In the UK market, the competition came from the Mini, the Ford Anglia and Vauxhall Viva.
Rootes conducted a theoretically thorough development testing programme for the Imp. In late 1961, cars were being tested in continental Euorpe ahead of cold weather testing in Canada in January 1962. These tests included the car being used for a commute in Montréal in January weather, and the consequent specification of a stronger battery, mounted in the rear engine compartment rather than the front, and of a stronger heater.
Cars were also being tested in hot weather conditions in East Africa, with findings including that the cooling was marginal, and that the cooling fan was vulnerable to stone damage.
Rootes obviously bench marked the Imp against the 1959 BMC Mini and a week before the formal launch, Fry showed the car to his personal friend, Alec Issigonis. Issigonis declared the car to be “brilliant but the wrong way round”. Issigonis and Fry would have passionate but good natured arguments about the configurations of their respective cars. Issigonis would quote a dart (“it has its weight at the front to keep it going straight”) and Fry would counter that “a dart can’t go round corners”.
And the Imp could go round corners, arguably better than a Mini. It had great traction coming out of them too, and the lightweight origins and sports history of the engine and the ease of use of the transmission were soon apparent, especially when matched against the BMC A series, where the gearbox in the sump had an awkward gear change, to say the least.
The Imp had a strong motorsport career, starting as early as 1964 when Rootes homologated a 998cc engine for the Rally Imp, and the car came first and second in the Tulip Rally in 1965.
The winner was Irishwoman Rosemary Smith, who went onto many more class wins and what were known as “Coupes des Dames”, and Rootes made certain the public knew about it.
Into the 1970s, rallycross and rallying featuring Imps and Minis was a regular Saturday afternoon television spectacle, and Imps are still seen in classic racing and rallying, even now.
The car was in the showrooms on 3 May 1963,with all the usual pomp and circumstance, including an official factory opening by the Duke of Edinburgh opened the new factory in Linwood, west of Glasgow. Many stories are told about this timing and the actual event. Given the value of the government grants and loans involved, the company was seemingly tied into the May 1963 date, despite Rootes’ new engineering director Peter Ware asking for another six months to complete the development and the production staff protesting they were not ready. Many transporters carrying Imps went past the Duke, or maybe the same transporters actually went past him many times…
Rootes had to build the Imp in Scotland, about as far from Coventry as industrial Britain could be, as government policies dictated that industrial development on this scale should be in a depressed area. Against that background, Rootes selected Linwood, rather Merseyside as chosen by Ford and GM at the same time, for the Imp.
The plant was directly adjacent a plant set up by Pressed Steel, which would supply not just pressings but pressed, assembled, painted and mostly trimmed out Imps to Rootes. Rootes also set up an extensive die casting facility for the engine and gearbox castings in Linwood, though these were all machined in Coventry. A train ran daily taking castings south and engines and gearboxes north.
The Rootes publicity people (voiced by the incomparable Raymond Baxter, of course) gave their side of the story, as ever.
Rootes, being Rootes, used different names for the Imp in various markets, often selling it as the Sunbeam Imp but also as the Sunbeam 900 in Scandinavia for example. And Rootes, being Rootes, soon started badge engineering the car in the home market as well. In late 1964, the semi-luxury Singer Chamois was offered, with wood trim and even a little false grille on the front, and in 1967 the sports brand Sunbeam joined in, with the Sunbeam Imp Sport fitted with a 51bhp version of the 875cc engine, and additional cooling slots on the rear bonnet lid. There are even rumours of Humber, Rootes’ luxury brand, being considered for use on the Imp.
The first significant revisions came in September 1965, in reality less than two years after the car was widely available. A new water pump, a revised cylinder head and gasket, a bigger radiator and more fan blades helped address the cooling and overheating issues; the pneumatic throttle and automatic choke (the lever ahead of the gearlever) were replaced with conventional cables, and there were other minor changes, not least of which were Mark II badges to make the point. The feature car is a 1966 Hillman Imp MkII, seen recently on UK ebay, and probably best looking Imp I can remember seeing, ever.
In 1965, the first style variation appeared – the Hillman Husky estate and Commer Imp van variation, with a roof raised by four inches to maintain a good load bed height over the rear engine. These were significantly more accommodating than a Mini van, though the Post Office turned them down, considering them too fast for the postmen, and stuck with the Morris Minor van.
The other major revisions came in 1968, with a new, arguably less modern but more conventional interior featuring a single plane flat dash with four instrument slots, some used only on the sports Sunbeam and Singer versions, and losing the second finger tip stalk, and revised (and improved) seats and trim details.
The other production body variation was the fastback Hillman Imp Californian (an old Rootes model name), Singer Chamois Sport and Sunbeam Stiletto variant of 1967, with a roofline 2 inches lower.
This was a very attractive style with a more steeply raked windscreen, and although these cars lost the versatility of the opening rear window, they gained a (the first?) split fold rear seat squab. Some versions, typically the Sunbeam and Singer 51bhp cars, had four headlamps, which fitted as if they had been supposed to be there all along.
The Sunbeam version had an alternative dash style as well, with a group of instruments arrayed around the steering wheel in a style not dissimilar to the 1968 Sunbeam Rapier/Alpine GT.
Something that never saw the light of day was a light commercial and small people carrier, roughly along the same lines as the VW Type 2.
Rootes also had a proposal for a compact light commercial designed for CKD assembly using deliberately simple body work in less developed countries.
One variation that was built, but only in prototype form, was this is saloon height estate-cum-full hatchback, and which was photographed as early as 1964. It lost out to the familiar Husky and van as Rootes could only justify one and the greater internal height of the familiar van was necessary. To me at least, that makes a visually more attractive car.
But after 1968, the Imp was effectively left to soldier on with next to no change, other than colours and a series of limited run special editions culminating in the Imp Caledonian, picking up on its Scottish connections.
The Imp made it to North America, from 1964 to 1967, as Sunbeam Imps (Paul Niedermeyer’s Imp CC is here) but figures suggest no more than 5,000 were sold.
But it was by no means a success and clearly not suited to that market, even if Billy Rootes shook hands with Cary Grant over one.
The Imp was in production until 1976, when after the UK Government bailed out Chrysler UK for £125m (say £700m or $1100m now) it was replaced at the foot of the Chrysler UK range by the Chrysler Sunbeam, a cut-down Hillman Avenger (Plymouth Cricket) with a sharp contemporary style. A version of the Imp engine, stretched to 928cc, mounted conventionally at the front and driving the rear wheels made the cut though, in a car that matched the Vauxhall Chevette/Opel Kadett City or Toyota Starlet very closely.
In volume terms, the Imp was a failure for Rootes. Production had been planned at 150,000 a year, but with the impact of the arguably premature launch, the reliability issues, the lead already established by BMC, the lack of experience of Rootes and its dealers in this part of the market and, I suggest, the layout of the car, volumes never approached the target. UK sales in 1963 were 33,000, rising to 50,000 in 1964. It then declined despite the improvements to the car and the wider range, to the extent that by 1968 it was down to 35,000. Almost half of the Imps sold in the UK were sold in the first 5 years; of 440,000 cars, 252,000 had been built by 1966. In 1969, Rootes built around 20,000 Imps, not 150,000; BLMC built 318,000 Minis.
This lack of commercial success was a factor, though not the only one, in the final decline of the Rootes Group and its takeover (or rescue if you wish) by Chrysler that started in 1964. Rootes needed to start paying back the government loans, and the projected volume was not there.
The Imp was an appealing car in some ways, with some innovation in materials, layout and ergonomics, hampered by some awkward manufacturing logistics, an ill-prepared marketing network against strong competition, and some technical issues and failures. It was in many ways a good car to drive, perhaps better than its intended market needed, and had motorsport success, but the unusual configuration, and early quality and reliability issues obscured that for many potential owners.
But the Imp was more than a car – it was also a heartfelt and genuine, if ultimately not fully successful, attempt to revive a depressed area and may have brought more benefit than it is credited with, and we should acknowledge that.
Thanks to fellow Curbivores Don Andreina for some of the development images.
If you want to know more about the Imp, try www.imps4ever.info, possibly the best single car website I’ve seen