A few days after Peugeot weighed in with its latest eco-friendly hybrid concept, French countrymate Renault followed suit. Its all-new EOLAB Concept slashes fuel consumption in half when compared to the already efficient Peugeot 208 Hybrid 2L, requiring just 1 liter for 100 km of driving (235 mpg) while puffing out just 22 g/km of CO2 (NEDC cycle).
While Volkswagen resorted to some pretty extreme design measures to create its 1-liter XL1, Renault has managed to reach 1L/100km with a car that doesn't look much different than the typical small hatchback. Of course, the EOLAB is just a concept car, not a production model.
Renault says the new B-segment compact uses nearly 100 technological design solutions to deliver its staggering fuel economy. Those innovations are split into three familiar categories: weight minimization, aerodynamic enhancement and powertrain economization.
Renault doesn't just add a few aluminum and carbon fiber parts when cutting weight; it reworks every major aspect of the car, beginning with the layout. The car's asymmetrical three-door design puts a single door on the driver side and two on the passenger side. Inside, the optimized seating set-up saves 12 kg (26.5 lb) and 30 mm (1.2 in) of overall vehicle length.
Renault's weight-savings program cuts some 400 kg (882 lb) of bulk when compared to the similarly sized Clio. A large chunk of the weight reduction comes from a multi-material construction consisting of a steel, aluminum and thermoplastic body and 4.5-kg (10-lb) magnesium roof. Renault says the roof weighs just under half of what an equivalent steel roof would weigh. Tempered window glass is dropped in favor of laminated glass and polymers, and the car features patented ultralight intake ducts made from expanded polypropylene.
The strategic material substitution continues inside. Renault plants slim, lightweight seats atop frames built from steel, non-ferrous alloys, carbon fiber and magnesium. Even small, seemingly insignificant parts like plastic trim pieces are reworked for weight savings, with Renault replacing the solid plastic with thin, foam-injected material, cutting weight by around 25 percent.
"You can always save weight if you’re prepared to pay the price, but that would be contrary to Renault’s philosophy," explains Laurent Taupin, EOLAB project leader. "Our strategy is to reduce weight in a way that benefits everybody. That means finding economically viable solutions that our customers can afford. Our approach can be summed up by the phrase: 'the right material for a given job.'"
From there, Renault's design benefits from what the company calls the "virtuous circle of shedding weight." The significant weight savings around the EOLAB's exterior and interior mean less mass to push forward and control, allowing for smaller hardware in the powertrain and running gear.
The "Z.E." hybrid drive combines a 75-hp one-liter three-cylinder gas engine with a compact 40-kW motor wired to a 6.7-kWh lithium-ion battery. The gas engine is linked to the third gear ratio of the clutch-less three-speed transmission, while the electric motor is mated to the first and second ratios.
In cranking fuel economy potential up to the impressive 1 L/100km (235-mpg) figure, the EOLAB can travel up to 60 km (37 mi) at speeds up to 120 km/h (74 mph) on electric power alone. Two driving modes help the driver balance electric and engine power. Weekday mode favors electric driving, providing all-electric first-gear driving at speeds up to 65 km/h (40 mph) and kicking up to all-electric second gear for speeds up to 120 km/h (74 mph). Beyond those speeds, the system activates the gas engine. Weekend mode switches the engine into action at lower speeds and balances electric and gas output toward efficient, long-distance driving.
Renault also lightens other hardware, including the brakes and steering. The concept uses the Continental MK C1, a vacuum-less braking system that is several kilograms lighter than conventional brakes. The design combines the brake actuation, brake booster and control systems (ABS, ESC) into a compact, single-piece unit that Renault says is well-suited to driver assistance and brake regeneration functions.
In terms of aerodynamics, Renault narrows the rear track, drops the roofline, optimizes the design of the rear body panels and adds active aero systems. The active aerodynamics package begins with the car's ride height. When the car is parked, the active air suspension system is at its highest setting to accommodate entry. Between 5 and 70 km/h (3 and 43 mph), it lowers by 25 mm (1 in), lowering another 25 mm at speeds over 70 km/h.
The narrow 145/45R17 Michelin tire-wrapped wheels also include active aerodynamics. When the brakes are cool, the system activates smooth wheel facings to improve aerodynamic performance. When the temperature sensor reaches a certain level, the wheels open to promote brake cooling.
The active aerodynamics package finishes off with a active spoiler that drops down at speeds above 70 km/h and rear bumper panels that open at that same speed threshold, keeping air wrapped around the car. The aerodynamic improvements result in a 30 percent drag reduction that Renault claims doesn't involve any accompanying passenger cramping issues.
With all that's going on around the car, the driver has a lot to keep track of, if he or she wants to remain fully informed. For that, Renault has designed a special Human Machine Interface built around a centrally-mounted tablet-style display and dual-display, height-adjustable instrument panel. The right instrument display is dedicated to GPS, while the left offers traditional information like speed and engine warnings. The 11-in tablet display can be oriented horizontally or vertically and shows an advanced breakdown of data pertaining to the car's efficiency: driving style, active aerodynamics status, gradient, tire rolling resistance and status of electrical equipment (e.g. climate control systems).
"Today, after a fashion, the majority of the systems available in the market give drivers just raw information (current consumption, average consumption, etc.) that don’t really enable them to make any progress," says Jean-Pierre Fouquet, Z.E. Hybrid Innovations project leader. "Courtesy of this graphic, drivers now have at their disposal the necessary tools to take charge of their own consumption."
Renault says that the EOLAB previews a B-segment car that will materialize in mass production within the next decade. While that gives the automaker plenty of time to switch directions and drop the EOLAB project, it does plan to gradually introduce the weight-savings, aerodynamics and mechanical innovations to existing models over the coming years, helping to improve efficiency across its entire lineup, including the development of a 2L/100km (117 mpg) car by 2020. It identified the EOLAB solutions with that goal in mind, seeking technologies that would be technically and financially viable in the near future.
"Today, most of the market’s hybrid vehicles are higher segment cars with a price tag of more than €40,000 (US$51,700)," says Foquet. "The solutions showcased by EOLAB are much more economical and enable hybrid technology to be used for smaller cars and on a much bigger scale. Our objective is to produce a car with two power sources for the price of one."
Renault will show two versions of the EOLAB at next month's Paris Motor Show. The rougher prototype version was built by its engineering department, while the more polished EOLAB Concept was developed within its design department.
"A technology demonstrator is rarely attractive, and a concept car is rarely realistic," says Patrick Lecharpy, vice president of Renault's Cooperative Innovation Laboratory. "That’s why we decided to develop two vehicles as part of this project. The aim was for technology and desirability to go hand in hand, to avoid a result that would be high-tech but cold."
Gizmag will be attending the Paris Motor Show and we anticipate spending some time with both EOLAB versions, updating you with more information and photos. In the meantime, you can get a closer look in our photo gallery and the intro video below.