When Peugeot built its Group B rally challenger, it little thought one of its customers would be Lotus Engineering
It was surprising to see a pair of Peugeot 205 Turbo 16 Group B homologation road cars for sale at the January 2018 Barrett-Jackson Scottsdale auction – because these cars were consigned by General Motors. One of the cars was listed as having ‘active suspension’, which warranted further investigation.
During the 1980s General Motors was heavily involved in active suspension systems; they built and tested several road cars at the Milford Proving Grounds in Michigan. Other such systems were also being developed across the pond by then GM-owned Lotus for use in Formula 1. Lotus Engineering subsequently started to test active suspension systems on road cars, first with the company’s own Esprit, then for GM models such as the Buick Park Avenue and Chevrolet Corvettes.
The active suspension development originally conceived for the F1 team in 1981/82 became a major technical offering for Lotus Engineering and ultimately grew into a suite of active systems for vehicle dynamics control. Circa 1984 Lotus secured a massive contract from GM to develop an array of active systems that would be showcased in the Corvette Indy concept car.
By this time Lotus had already built several cars with active suspension for GM and had sold Volvo a scheme for creating active rear steer that worked very well. So Lotus had already gone beyond just active suspension. The particular concept that Lotus was working towards for the Corvette Indy project was ‘active everything’ – the ultimate goal being the ability to control all of the forces at the tyre contact patch and thus achieve maximum performance.
For this special project, Lotus Engineering needed some new tech and some mule vehicles for test purposes; cars that would have lots of performance, be four-wheel drive and, ideally, be quite easy to modify. While the engineers did look at building something from scratch, they also analysed all of the cars around at the time, ultimately landing on the then-current crop of Group B rally cars. The MG Metro 6R4 was a possibility, as was the Ford RS200, but Lotus eventually purchased the last two 205 T16s (chassis 048 and 091) from Peugeot Talbot Sport’s André de Cortanze.
When the cars were delivered to Lotus they were brand new, so they first had to run them in as road cars. Patrick Peal, one of the engineers involved in the project, remembers the experience as “Quite a hoot! I took one from my home to Brighton for the weekend to visit some friends. I discovered pretty early on that if I gave it full throttle for an instant and then backed off I could get a huge flame out of the exhaust – a good effect in the high street at night… It still makes me smile – and there are still people around Brighton talking about the flame-spitting 205 on steroids!”
Project manager Steve Green also recalls driving one of the Pugs: “I knew it would pull 7500rpm in fifth gear, about 130mph, because I did that at GM’s Van Dyke test track, then got told there was a 70mph speed limit… Oh well!”
This excitement was aided by the fact that Lotus decided that the 197bhp of the standard car wasn’t enough, bearing in mind the power drains and added weight of the future special systems such as hydraulics, so they decided to purchase the PTS kit or Clubman upgrade from Peugeot Talbot Sport, which would net a more capable 300bhp along with other chassis improvements.
After the joyrides were over, Lotus went to work developing and fitting chassis 091 with fully integrated active systems. Such sophisticated engineering required a benchmark to make sure that it truly had improved overall performance, so the other 205 Turbo 16, chassis 048, was kept standard for reference.
THE JOURNEY OF the Corvette Indy mule had begun with the fitment of Lotus’s famed technical offering: active suspension. The purpose was to keep the car’s body flat and level during braking and cornering at the limit of adhesion. To achieve this, the system constantly measured pitch, yaw and tyre slippage on all four wheels, making adjustments as needed by hydraulic actuators that replaced the conventional springs. This required a big hydraulic pump to maintain the high pressure needed to raise or lower each corner almost instantly in response to sensor inputs.
The project continued by modifying the standard four-wheel-drive system of the Peugeotwith a second differential driven by a hydraulic motor, a sort of ‘tank drive’ system, so that the engineers could accurately control the speed of the front axle compared to the speed of the rear axle and therefore control slippage.
To do so, the engineers had to compare wheel speed versus true vehicle speed (longitudinally and laterally), which was a challenge. To perform this seemingly simple yet very complicated task, Lotus ended up using two Leitz Correvit optical speed sensors mounted behind the passenger seat and reading through holes in the floor.
These sensors were a bit like two massive telephoto lenses and were “a pig” to install, calibrate and keep working, Peal remembers, as they often had to calibrate the lateral speed sensor using a belt sander as a simulated road surface whose belt speed could accurately be measured.
And of course rear steer could play whatever static tricks the Lotus engineering team could dream up as well; same-sense, or opposite-sense giving a crabbing motion, or a very rapid rate of rotation within a small turning circle. In fact, one of the team’s party tricks was to apply full lock and full throttle and get massive burnouts in a ridiculously small circle.
“This left two very black and very small concentric circles on the test track, not much bigger than the wheelbase of the car. Oh, and a dizzy driver,” says Patrick Peal.
The rear-steer system was entirely developedby Lotus and was bespoke for both the 205 T16 and the technical demands of the project. Steve Green explains how it should not be confused with Nissan’s offering of the time.
“Nissan’s HICAS was a much simpler system although it did do some similar functions to the system developed for the T16. Ours was a lot more sophisticated and designed to explorewhat was possible as an R&D exercise.”
The ‘brain’ of the whole operation was fitted under the front bonnet – featuring a digital computer connected to the various active systems via an array of data and electrical cables. This effectively took away the space formerly occupied by the spare tyre. Technical director Peter Wright recalls the car also being equipped with anti-locking brake and traction control systems activated via ‘pedal pushers’
“We did very little development on these two systems, although I do remember we got them working and they were reasonably effective.”
There are few clues to the presence of all these special system from the outside, with the exception of a single canard-like appendage on the right side engine panel. This bodywork extension was needed to allow the engineers to fit part of the system around the engine.
Lotus then proceeded to test the full battery of active systems quite extensively in various venues around Europe; UK, France and even on an ice lake in Sweden. This would tend to be confirmed by the car’s odometer currently sitting at 15,915km. The benchmark car in comparison had its odometer reading just 2192km at the time of the Scottsdale sale.
“I remember that the torque control system was very noisy, and one could tell whether it was understeering or oversteering while sitting in the office, just by hearing it out on the track,” says Peter Wright
Once Lotus had sorted it all out the main project was then to build the Corvette Indy. However, there were some major problems that left the concept car as a non-functioning showpiece in 1986. By then the two Peugeots were already shipped out to America, where they sat as part of the GM Heritage Collection for about three decades before being sold off at auction this year.
After the defunct Indy project, GM shifted its intentions to an attempt at implementing active suspension into the production Chevrolet Corvette ZR1. Again, further problems and exorbitant costs prevented this from happening. The active systems developed with the Peugeot mule were ultimately ‘rebooted’ in the 1990 Chevrolet Engineering Research Vehicle, CERV III.
“The systems were awesome,” says Peal. “We were all very sad to say goodbye to the two Pugs when they were shipped to America at the end of the project.
“Some 1980s sports-prototypes require ancient laptops to fire up their electronics”
Green adds: “The car in its standard form was pretty good already, although it needed a certain amount of commitment from the driver to fully exploit its performance. The active version was an amazing machine and we learnt a lot about vehicle dynamics from it.”
Wright: “It was a great project and it’s good to know the cars live on.”
THE TWO ‘DETROIT LIONS’ would collect warehouse dust somewhere in America up until 2018, when GM ultimately decided that it was time to part ways with these cars and consigned them to the Barrett-Jackson Scottsdale Auction in January. Chassis 048 found a new owner who says that while the Peugeot is seemingly missing some upgrades normally found in the Clubman / PTS package, he nonetheless plans on enjoying the car with occasional drives up the scenic American west coast.
The active car, chassis 091, has not yet found a new home. It apparently still sports most if not all of the special systems implemented by Lotus, and perhaps that alarms buyers. After all, some 1980s sports-prototypes require ancient 486 laptops to fire up their primitive electronics…
Not much is known of how much of Lotus’s hard work might have directly ended up affecting other projects at GM. However, with all of the rumours of the next (C8) generation Chevrolet Corvette finally going mid-engined, possibly with active systems,it would be tempting to trace its lineage back to the Indy/CERV III and its Peugeot mule. If the future yields such a product, then perhaps you’ll need to be thanking the little Pug.