Lotus M70 and Esprit S1 and S2


Lotus Esprit S1 - Click on image to enlarge

In 1970, Tony Rudd, who had joined Lotus in 1969 and would soon be appointed Technical Director, had recommended the design of two major new Lotus models: the first, the M50, was the front-engined Elite and the second was the M70, a mid-engined machine intended to take over the mantle of the Europa. M70 was envisaged as a two-seater fixed-head coupe, with something of a wedge theme in its shape, and it was always intended to use a much as possible of the new running gear being developed for the M50/M52 Elite/Eclat cars. Like the M50 and M52, the new mid-engined M70 was given approval by management, though there was no way that design work on the new car could begin at once. Lotus’ resources were still quite slender, and management first chose to concentrate on finalizing the Type 907 engine and the development of the front-engined cars. The launch of a new design of mid-engined Lotus looked so remote that there was time for the Europa to be redesigned, not once but twice. Mike Kimberley was given the job of transforming the Europa, and in the autumn of 1971 the Renault-engined S2 was dropped in favour of the Europa Twin-Cam, a similar-chassised car powered by the 105bhp version of the Lotus-Ford twin-cam engine. This new car also featured a restyled rear bodyshell which offered better rear and three-quarter-rear visibility, and it as cast-ally road wheels, though the existing Renault four-speed gearbox was retained.


The new Twin-Cam – which was Type 74 in the Lotus scheme of things – had a top speed of 117mph, 0-60mph acceleration in 7 sec and typical fuel consumption was about 25mpg (Imperial), a considerable improvement on the Renault-engined car. However, the Twin-Cam had a short life, for just one year later, in the autumn of 1972, it gave way to the Europa Special, which was effectively an uprated version of it, with the more powerful, 126bhp, ‘Big-Valve’ engine and a five-speed Renault gearbox. Performance was boosted yet again, this time to provide the little car with a top speed of 125mph and 0-60mph acceleration in 6.5sec. It set a very high standard indeed, and whatever was chosen to replace it would have a very difficult job to do. In two distinct ways, however, it was going to be fairly easy to improve on the Europa – in the styling of a new car, and in the space offered to the passengers. The Europa, while always being immediately recognizable, had never been considered as an outstandingly attractive car, and even in its final developed guise it was most certainly not equipped with a very spacious cockpit. Like the two-seater Elan which preceded it, the Europa was a motoring machine rather than a passenger car. The M70, when it came along, would have to be more practical than this.


The styling of the new car, if not its engineering, began in 1971 following a chance meeting between Giorgetto Giugiaro and Colin Chapman at a motor show. Even in the early Seventies, Giugiaro had a formidable reputation as a stylist/designer, having started his career at Fiat, before moving on to Bertone, then Ghia, prior to setting up his own business, Ital Design, in 1968. Chapman knew all about Ital Design, and everyone knew about Lotus, so there was never any lack of understanding between the two. Quite simply, it seems, Giugiaro wanted to know if he could work up a special body style on a Lotus, and Chapman, with the M70 in mind, agreed to let him work on the basis of the mid-engined Europa.


An early Giugiaro sketch of the Lotus Esprit

Giugiaro had already produced the attractive mid-engined Bora for Maserati, and was working on the very angular, but startling advanced Boomerang project on the same chassis, so he was familiar with the challenges inherent in mid-engined layouts. To put it baldly, the very first Giugiaro style for Lotus was on the basis of a much-modified Europa Twin-Cam chassis, but since the Type 907 engine was soon to be installed, and the track and wheelbase dimensions were also altered, it is easy to see how Colin Chapman’s mind was working. The Europa’s wheelbase was 7ft 7in, and its widest track was 4ft 5.5in. Equivalent dimensions planned for the M70 – which did not have a name at this stage – were 8ft and 4ft 11.5in, respectively, so it was not surprising that the chassis supplied to Italy, thus lengthened and widened, was not Lotus’ final word on the subject. Work began on the style in mid-1971, and was completed before the end of the year, not as a running car, but as a full-size mock-up in display trim. A second car, not only with doors which opened, but with a more advanced and integrated design of chassis, followed in 1972. It was the original silver painted car – now remembered at Lotus, logically enough, as ‘the Silver Car’! – which made its public debut on the Ital Design stand at the Turin Motor show of November 1972. Even at this stage, Giugiaro had dubbed it ‘Esprit’, defined by the Concise Oxford Dictionary as: ‘sprightliness, wit’, and students of styling evolution will want to be reminded that it stood alongside the Maserati Boomerang at the show. The first Lotus-chassised Esprit, actually being on a much-modified Europa Twin-Cam chassis, which Giorgetto Giugiaro showed on this Ital Design stand at Turin in November 1972. The screen on this first car was even more sharply raked than the production cars were ever to be. The Maserati Boomerang alongside the Esprit shows signs of the same style thinking by the talented Italians.


The Lotus Esprit Clay Model

Something, for sure, was already on the move, and it was not long before motoring enthusiasts began to put two and two together. Mike Kimberely recalls that Lotus’ reaction to the completed prototype Esprit was so favourable that a design and development team was immediately set up to work with Giugiaro, and they stayed in Italy for a least 18 months. Chapman and Kimberley flew to Turin at least twice a week, during which the body style was refined and turned into a producible proposition. After the tremendously favourable public showing of 1972 there was a considerable lull while mechanical design commenced, though in the Group Lotus company report published in mid-1973 one of the three pictures published under the heading ‘The Coming Generation?’ was of the Giugiaro prototype, which had already been adopted by the company. The first true production prototype was nearly completed by Christmas 1974, and was actually driven to London’s Heathrow Airport to meet Colin Chapman when he returned from the Argentine Grand Prix in January 1975. Indeed, by this time, Lotus had confirmed that the Esprit would be launched during 1975.


A view of the original silver Europa-based Lotus Esprit of 1972. There were, of course, many differences in detail style between this car and the definitive version. Apart from the rake of the screen, note the type of louve behind the nose panel, the twin wipers and the way in which the rear of the body was arranged to open.

Lotus esprit 1972

The Lotus Esprit and Maserati Boomerang on the Ital stand in 1972

The design and evolution of the new Type 907 engine was always intended also to be used in Lotus’ new mid-engined car. It was, of course, an ideal package for the Esprit, compact in length, wide but not high, and – considering the power output – a very light unit. Both the cylinder block and the cylinder head were cast in aluminium, which was ideal for the Esprit, where there was bound to be a weight bias towards the tail. For the original Esprit, therefore, Lotus specified a 2-litre version of the new 16-valve, twin-overhead-camshaft engine. As fitted in the Esprit’s engine bay, behind the cabin, its installation and tune was exactly like that adopted for the front-engined cars. Complete with two twin-choke Dellorto DHLA carburettors, it was rated at 160bhp (DIN), and was installed with the cylinder block leaning over at 45deg towards the left side of the chassis. Unavoidably this meant that there was a slight weight bias towards the left side of the car, but not even the most experienced testers could pick up any effect on the handling so this detail was speedily forgotten. To provide more interior passenger space and to allow for the use of the more bulky Type 907 engine, the wheelbase of the M70 was to be 8ft, or 5in longer than that of the Europa which it would replace. It was also destined to be a much wider car than the Europa, though it was always intended to feature a steel backbone chassis-frame. Right from the start, Lotus’ biggest problem was to find a suitable gearbox, and this was critical to the entire project. Since the Type 907 engine pushed out 140lb.ft of torque, even in 2-litre form – and the highest figure reached by the ‘Big-Valve’ Lotus-Ford twin-cams had been 113lb.ft – it was clear that the five-speed transmission from Renault, as used in the Europa Special, would not be strong enough for the job.


Chapman already knew that it was not financially viable for Lotus to design, tool and build their own transaxles – the five-speed gearbox for the Elite/Eclat cars used standard British Leyland gear clusters – for the cost of tooling up for cutting gears was immense, so Lotus had to look around for an off-the-shelf transaxle. At the same time, they had to consider the V8 engine project, which would produce a great deal more torque than the 2-litre ‘four’. Because Lotus were financially independent of any other motoring manufacturer, they could go shopping for a transaxle almost anywhere. But it was not as simple as that. They were looking for a five-speed transmission with not only ample reserves of strength, but one which satisfied their desire for mechanical ‘elegance’, was light enough and was guaranteed for continuity of supply for many years to come. With regard to the later they were very wise, as the search for the transmission began in 1971, the first production units were not fitted until 1975-76, and they were still being used in the mid-Eighties.


The pre-production Lotus Esprit IDGG 01 (Ital Design Giorgetto Giugiaro 01)

The search for the transmission eventually ended when Citroen offered Lotus the use of their five-speed all-synchromesh gearbox/final drive unit, which was being used not only in the exotic front engine/front-drive SM coupe model, but also in the mid-engine/rear-drive Maserati Merak coupe. The timing of the deal was important, for even in 1972 the SM was a young design at the peak of its popularity, and the Maserati Merak had still not been announced. The SM transmission was a derivative of the five-speed gearboxes available on the other large DS saloons and estates, and Citroen were able to offer supplies for at least the next 10 years. Even though the SM is now long dead and the Merak was dropped in the early Eighties, Lotus never had supply problems from France. The gearbox was a conventional two-shaft design – conventional, that is, by transaxle standards – with the output of the spiral-bevel final drive from the second shaft. Its crownwheel and pinion design and the final drive casing were such that it could be run the ‘right way’ or ‘wrong way’ round – the Citroen SM and Merak installations, of course, work in opposing directions. A variety of internal ratios and final drive ratios could also be provided. In the end, those chosen for the mid-engined Lotus were the same as to be found in the SM coupe, the original Merak and the later Merak 2000, but slightly different from those used in the more powerful Merak SS.

Lotus Esprit 1975


The Lotus Esprit on display at the British Motor Show 1975


With the general layout of backbone frame chosen, the engine and transmission design finalized and the front suspension basically being the same as that fitted to the Opel Ascona/Vauxhall Cavalier, the rest of the mechanical design soon slotted into place. The independent rear suspension was as simple as possible; the fixed-length driveshafts doubled as upper transverse suspension links, combined coil spring/damper units were chosen, and large box-section semi-trailing radius arms helped to locate the wheels along with lower transverse links. Steering was by rack and pinion – but without power-assistance, no Esprit, not even the Turbo, ever having needed this – and the dual-circuit Girling brakes had front and rear discs, solid but not ventilated, with rear discs mounted inboard. There was no servo assistance. Wheels were cast-alloy 14in diameter Wolfrace items, with 7in rims at the rear and 6in at the front. Much work went into productionizing the startling Giugiaro shape, not only to make it easier and cheaper to build in quanity, but to make it meet all the regulations likely to face such a car in the mid-seventies. The most significant change was to the angle of the windscreen. On the original ‘Silver’ prototype the screen had been angled at a mere 19deg from horizontal, and to meet the regulations this had to be lifted to 24deg 5min. Colin Chapman, however, did not give in without a fight, and the production Esprit still kept the same dramatically swept screen pillars, a feature achieved by making the screen profile much less curved in plan than had originally been intended.


Interior of the Lotus Esprit S1

The interior layout and facia were retained as much as possible and there was a great deal more space for two passengers, but no briefcases or other luggage could be stored in the wide cockpit. There was no space behind the seats, the cover over the backbone chassis-frame between the seats was high and wide, and there was only one storage container, ahead of the passenger’s knees. As in the Europa, the seats were steeply reclined, and to climb in and out of the car was not for the modest or the unathletic. In the meantime, there had been momentous changes at Lotus, both to the fortunes of the company and to the personalities at the top, Dennis Austin, Managing Director of Lotus Cars since 1969, moved on in 1974 and was replaced by Richard Morley, while Mike Kimberely, who had become Vehicle Engineering Manager in 1972, took over the title of Chief Engineer – from Tony Rudd – in 1974 and would be elevated to the Lotus Cars Board at the end of 1975. Tony Rudd became Group Research Director, a position he held until the early Eighties, when he was attracted back into Team Lotus and Grand Prix racing.

The Esprit was not ready for production when it was announced in October 1975, but for several good political reasons Lotus thought it necessary to reveal the car at the same time as the Eclat, which was ready. The car, after all, had already been around for three years by then and was known to the public; Lotus were worried that their customers would despair of it ever being announced if they did not show it then. The combination of energy crisis/oil shock, the launch of the M50 Elite and the progressive withdrawal of the Elan, Plus 2 and Europa families hit Lotus finances very hard. Pre-tax profits in 1973 had been £1,155,700, but they plunged to £293,909 in 1974 and losses were forecast for 1975. Faced with this sort of situation, the company had to retrench, and Lotus now confirm that the Esprit was delayed by about nine months due to this financial stringency. In normal circumstances, therefore, the Esprit would have been ready for deliveries to start on announcement in the autumn of 1975. The delay ensured that tooling was not complete by then, so that the first series production car was not commissioned until May 1976, and deliveries began in June and July. It is worth recalling that the Esprit’s UK price was fixed at £5,844 in October 1975 – when the comparable Elite 501 price was £6,493 – but this had rocketed to £7,883, representing an increase of 35 per cent by the time deliveries began. If Lotus had ever held hopes of producing a direct, but more upmarket replacement for the Europa Special, which had been dropped in 1975, they were now dashed. It was doubtful if the original published prices of October were realistic, for company cost accountants do not have to make such huge adjustments in a matter of months.


Early promotional picture of the Esprit S1

Few people would now argue with the opinion that the original Esprits were disappointing cars, for they were neither as fast, nor a refined or reliable as Lotus had hoped. For this, Lotus could certainly not blame their supplies, for the Lotus-built content of the car was approaching 70 per cent by value. The practical limits had already been reached, for the majority of the other 30 per cent went to pay for components such as the Citroen gearbox, wheels and tyres, electrical equipment, springs and dampers. Lotus claimed that the original Esprit should have reached 138mph, but Autocar’s test car managed only 124mph, and Motor confined itself to a figure of ‘more than 125mph.’ This shortfall, however, was not as serious as the lack of refinement in the car, for much of the engine noise was transmitted to the cockpit, and the overall impression was one of hashness. The press, in general, though that more than three years of development should have seen this ironed out before cars were delivered to customers. Perhaps this special Esprit was not quite as amphibious or versatile as the James Bond film The Spy Who Loved Me suggested, but it certainly made very good publicity for Lotus in 1976. Even so, no-one could argue with the car’s remarkably sexy good looks, handling, general road behaviour and its overall effect on every other motorist – not least the gentlemen in blue!

Lotus Esprit Spy Who Loved Me

A Promotional shot for the James Bond Film, The Spy Who Loved Me, with Roger Moore, Barbara Bach and the Lotus Esprit S1

The use of early Esprits in films like the James Bond epic, The Spy Who Loved Me, where the car, or things mocked up to look like the car, were made to perform incredible feats, must all have helped. More than anything else, the Esprit was intended for sale in the United States. Peter Pulver, who was Lotus’ principal Stateside distributor, ordered 150 cars at Earls Court in 1976, the first Federal Esprit was commissioned before the end of that year and deliveries began early in 1977. The Type 907 engine, complete with twin Zenith-Stromberg carburettors, came through the emission-reduction tests with such flying colours that the net power output was still as high as 140bhp, so that the car had a top speed of 120mph in fourth or fifth gears (Road & Track, July 1977), all for an East Coast FOB price of $15,990 or – more importantly - $16,844 in California. The USA launch had a dramatic effect on Esprit production, which had been 138 in 1976, but rocketed to 580 – the best Esprit year ever – in 1977. In 1976 all but four cars were built for the UK, but in 1977 no fewer that 474 were built for the USA. Nevertheless, criticism and adverse press comment about the original Esprit had struck home, and Lotus made speedy attempts to improve the car. The result was that the S2 model was launched in August 1978, just over two years after the first Esprit deliveries had been made. Second thoughts, in this case, were wise ones, for the S2 was an altogether more integrated package.



The Esprit S1 with a glamorous lady


Here is a late model Lotus Esprit S1, with Esprit S2 Speedline alloy wheels, parked outside the Hethel HQ

Mechanically, there were few changes to the S2 compared with the S1, except that the ‘E-camshaft’ specification introduced on late-model S1s was now standardized – with a worthwhile improvement in mid-range torque – and Speedline road wheels replaced the original Wolfrace variety. Externally, the most obvious improvement to the style was the front undernose spoiler was now smoothly integrated into the shape of the car, while slightly protruding engine compartment air intakes were neatly positioned behind the rear quarter-windows. At the rear of the car Rover SD1-type tail-lamp clusters were fitted. Inside and underneath there was a twin electronic motor lift mechanism for the headlamps, a new instrument cluster and slide-type switches, recontoured and wider seats, a digital clock, a redesigned engine cover and a revised aluminium sprayed exhaust system. In case potential customers still couldn’t tell the difference, there was an ‘Esprit’ decal on the nose instead of the ‘Lotus’ of the first cars the ‘Esprit S2’ decals on the rear quarters. The UK price, however, had rocketed once again, for the inflation rate was still quite shameful. In August 1978, therefore, the Esprit S2 was priced at £11,124 – 9 per cent higher than the last of the S1s. Lotus publicity chiefs were delighted to announce that Team Lotus’ contracted drivers, Mario Andretti and Ronnie Peterson, had taken delivery of the first two production S2s.


Lotus Esprit S2 Cut through


Minor body changes to the Esprit S2 included a more integrated front spoiler and neat air intakes into the engine compartment positioned at the trailing edge of the side windows.




Click on image to enlarge

There was on interesting mechanical innovation, made as much to suppress costs and to minimize the use of front underbonnet space as good engineering reasons: the spare wheel now had a 5.5in wide rim and carried a small 185/70HR-13in tyre. It was a mere ‘get you home’ spare, not intended for prolonged use after a puncture. Lotus, however, were not content with launching this new derivative, for they also produced a special ‘Limited Edition’ Esprit S2 at the first NEC Motor Show in October, which was decked out in black and gold ‘JPS’ livery to commemorate the Lotus 79/Mario Andretti feat of winning both Formula 1 World Championships; 100 of these cars were built, each individually numbered by a plaque on the dashboard, signed by Colin Chapman himself. S2 performance was nearer to the original claims – Autocar’s car was good for about 130mph, with 0-60mph acceleration in 8sec – and the drag coefficient of 0.34 was virtually unaffected by the changes to the style. All in all, this was a step in the right direction, even if there were still advances to be made in refinement, reliability and overall creature comforts. Lotus had all these points in mind, and the launch of the Chrysler Sunbeam-Lotus in March 1979 hinted at the way they might move next. The Sunbeam-Lotus, after all, had an enlarged 2.2 litre engine. Would in-house Lotus models soon follow this development?


Click on image to enlarge

Taken from Lotus Since the 70s by Graham Robson