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Fitting the bill: Renault's rear engine Twingo shares its Tridion safety cell cabin structure with its smart cousin and features a Daimler-designed and Renault-built three-cylinder engine. The French OEM has a long history of rear-engine/rear-drive cars including the famous high-performance Renault Alpines. (For more images click on the small arrow in the upper right corner of this image.)

Daimler and Renault-Nissan marriage bears rear-engined offspring

Engineering and design collaborative projects between OEMs have become relatively commonplace regarding powertrains and components, but such relationships also can be surprising. A recent one is the link between premium producer Daimler, maker of smart minicars and Maybach S600 limousines, and the Renault-Nissan Alliance whose nameplates span Dacia to Infiniti.

Already the deal, signed in 2010, "has accelerated the time-to-market for significant vehicle launches for Renault-Nissan,” claimed company Chairman and CEO Carlos Ghosn. His latest colleague Dr. Dieter Zetsche, Chairman of Daimler and CEO of Mercedes-Benz Cars, promised the companies "will continue to work together in the future — with joint projects that establish a win-win situation for all partners involved.”

The most surprising offspring of their union are smart’s new generation fortwo (two-seat) and forfour (four-door, four-seat) models, and Renault’s little Twingo, all now entering international markets. Designed from scratch, they share a rear-mounted engine (engineered by Daimler and supplied by Renault), Getrag dual-clutch transmission, and a host of other components. Depending on version, some 60 to 75% of the overall bill of material are common between Twingo and forfour, states Renault. However, 95% of those visible to the customer are different.

Dieter Rohkohl, smart's Design Project Manager, is a key member of the liaison teams working with Renault. He was fully aware at the outset of the collaboration that although rear-engine powertrain solutions had been part of Renault’s model range in the past, they certainly were not part of its current modular strategy and therefore might be regarded as difficult to execute.

A dozen projects and counting

In fact Renault had considered rear-engine architecture for its next-generation Twingo but deemed it too expensive to produce profitably. Then along came Daimler looking for a business and technology partnership for its next-generation smart, which happened to feature a rear-engined layout. This helped establish an association between the companies that offered the right manufacturing scale for rationalizing a rear-engine Twingo. With 17 years' production, smart had demonstrated convincingly that a rear engine configuration remained an elegant engineering solution for city-type cars, said Rohkohl.

A rear-engined Twingo concept also appealed to Renault’s marketing specialists, he told Automotive Engineering: “It would offer differentiation amongst the French OEMs and distinguish the Renault product,” Rohkohl noted.

There is far more to come from the link-up, with Nissan and Daimler scheduled to co-develop and manufacture premium compact vehicles. At a jointly owned facility at Aguascalientes, Mexico, close to an existing Nissan plant, production of Infiniti models starts in 2017, with Mercedes models following a year later. Total annual production capacity of the plant will be 300,000 units.

Further premium compact vehicles will also be produced at other Daimler and Nissan plants; the companies are now sharing a dozen projects in Europe, Asia and North America.

The companies have close powertrain links. As well as the three-cylinder engines for the two smart models and its own Twingo, Renault is supplying 1.5-L and 1.6-L four-cylinder diesel engines for several Mercedes-Benz model lines (including A, B, CLA and C-Class), while a 2.0-L turbocharged gasoline unit is jointly produced at a Nissan and Daimler facility in Decherd, Tennessee, for both the C-Class and the Infiniti Q50.

The smart forfour is technically the same platform as the Twingo with the same wheelbase (overall dimensions of the two cars vary slightly) and firewall, steering wheel and seating positions are all the same. Although both also share the same basic three-cylinder engine, there are two capacities (0.9-L and 1.0-L), and three power levels: 45kW (60 hp), 52kW (70 hp) and 66kW (88 hp, turbocharged). There are differences between smart and Renault in transmission-control calibration. ABS and ESP systems’ operation are also different.

The previous forfour was also a collaborative program, but with Mitsubishi, which produced it as the Colt, both being built by NEDCAR in the Netherlands. The new forfour and Twingo are being manufactured at Renault’s Novo Mesto, Slovenia plant, while the fortwo comes from smart’s Hambach, France facility.

EuroNCAP synergies

Rohkohl said the origins of the new model can be traced back seven years when the search began to find the right partner. “The decision in favor of Renault was a very conscious one and we are confident that we have created a win-win situation for both parties—for example, smart is a specialist in rear-wheel drive systems, Renault for small engines," he explained.

A key factor in the decision to cooperate was "the retention of the rear engine concept along with production standards of the highest quality," Rohkohl said. "In Renault, we have found a partner who shares the priority we give to these issues, which for us are fundamental.”

An added plus was Renault’s experience in passive safety design, with outstandingly good EuroNCAP results. So there was an exchange of expertise between the companies. One aspect of that was that Renault did not have the specific body-in-white expertise for smart’s Tridion safety-cell cabin design, which is similar to that of the previous generation smarts.

“If both sides are open to the situation, each can benefit,” stated Rohkohl. The smarts and Twingo achieve 4-star-level EuroNCAP testing results under the recently introduced tougher criteria.

Styling of the cars was executed independently by each company to ensure required marque identity. Observed Rohkohl: “Almost every month we had a meeting in Paris looking at differences—and what makes a Twingo a Renault and a smart a smart.”

Whole-car safety testing levels for smart meets Mercedes-Benz Cars’ own internal standards, stated Christoph Schulenberg, Head of smart Testing. As well as meeting legislated crash safety requirements, smart/Mercedes-Benz has its own “Real Life Safety” car-to-car crash test programs.

“For example, they include a frontal collision with a much larger and heavier Mercedes-Benz S-Class," Schulenberg said. "It is not a legal requirement but it fulfills Daimler criteria.”

The Tridion safety cell of the smarts and Twingo incorporates ultra-high-strength (UHSS) hot-formed steel and maximum strength multiphase steel.

The smart fortwo is available worldwide including the U.S.; at present, the forfour is not on sale in North America. The new Twingo will be sold into 20 countries outside North America.

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