In addition to the aforementioned technologies, PEUGEOT is applying its skills across the gamut of automotive applications to continuously lower fuel consumption and CO2 emissions. The weight savings achieved on the 208 and 308, which respectively shave off 110 and 140 kg on average, have helped reduce fuel consumption to just 3.4 and 3.2 l/100km for diesel models. Petrol equivalents stand at 4.1 and 4.6 l/100km.
Continuing its proactive approach, PEUGEOT is showcasing its 208 HYbrid Air 2L technology demonstrator at the Paris Motor Show. The demonstrator provides a snapshot of the full range of technologies used in meeting the government's goal of achieving a fuel efficiency of just 2.0 l/100 km. The project includes one unknown quantity, however: it must be possible to affordably manufacture relevant technologies on an industrial scale by 2020.
As a result, the demonstrator sets the bar high with the bid to halve the consumption of an already highly efficient 208!
Achieving this goal requires a focus on a number of key factors. Even shedding the slightest gram of CO2 is a huge challenge. According to the New European Driving Cycle (NEDC), a 1 g reduction corresponds to:
- a weight reduction of 10 kg;
- or a 50 W reduction in electricity consumption;
- or a 6 N reduction in rolling resistance;
- or an improvement in SCx of 0.03 m².
What is more, a 1% improvement in engine efficiency can reduce CO2 by the same amount.
The 208 HYbrid Air 2L technology demonstrator is based on the mass-production model, the 208 1.2-litre PureTech 82 BVM5, which has the following specifications:
- consumption: 4.5 l/100;
- CO2 emissions: 104 g;
- weight: 960 kg;
- SCx: 0.65 m².
To lower fuel consumption to 2.0 l/100km, PEUGEOT engineers and project partners used technologies previously reserved for competition and luxury models. They embarked on a meticulous selection process to choose only those compatible with existing production facilities and a high manufacturing output. In addition, the process involves reducing consumption without altering the car's characteristics, retaining a style synonymous with high-end products and services.
A weight of just 860 kg
The series-production PEUGEOT 208 makes extensive use of steel in both the structure and trim of the vehicle. With a density of 7,850 kg/m3, the use of alternative materials such as composites and aluminium offers real potential. They provide density in the region of 1,200 kg/m3 for a carbon composite and around 2,700 kg/m3 for aluminium. However, it is not always possible to replace a steel part with a similar part made of aluminium given the need to take into account the mechanical properties and cost of materials.
This use of multiple materials in the design process creates a real challenge. The goal is to assemble vehicles using a mix of steel, aluminium and composites while developing new assembly technologies. This is one of the focal points of the project.
The steel structure houses a new floor pan made of composite materials that helps to absorb energy in the event of a collision. These materials undergo electrophoretic deposition (EPD) during the manufacturing process, creating a composite floor that comprises three parts bonded using thermoplastic technology.
The stiffness of the composite materials is also used to simplify the design of some parts. The tailgate features a "semi-structural" design that consists of a skin and a lining with a thickness of 1.5mm to prevent torsion. This eliminates the need to add additional strengtheners in flat areas by optimising the direction of the carbon fibres in relation to the direction of the forces acting upon them. The stiffness and reduced density have also made it possible to remove one of the two stabiliser jacks to further reduce weight. A groove is also moulded into the lining to accommodate the electrical cables and reduce the number of fasteners.
Carbon composites are used for the body panels, sides, doors and roof, along with the coil springs providing suspension. In the latter case, the use of composites has a positive impact on dynamic handling by reducing unsprung weight.
The engine mounting, rails and side members are made of aluminium, a metal with good kinetic protection. Oxidation naturally covers the aluminium in a fine layer of aluminium oxide, which protects it against deep corrosion. Aluminium can also be recycled without altering its mechanical properties.
However, the campaign to reduce weight has not focused solely on the use of new materials; it has also sought to redesign existing parts. This has led to changes in the thickness of the stainless steel exhaust system, enabling a 20% improvement on this part alone.
Based on a particularly lightweight mass-production 208, the 208 HYbrid Air 2L demonstrator achieves significant weight savings. Changing materials, redesigning parts and introducing new processes has shaved some 100 kg off the weight of the vehicle.
A drive train that combines efficiency with driving pleasure
The standard 208 1.2-litre PureTech 82 has a petrol engine and five-speed manual transmission. This has been replaced by a hybrid drive train featuring a mix of petrol and compressed air. HYbrid Air technology combines two types of energy to achieve greater efficiency depending on the driving conditions. The compressed air is used to assist and even replace the petrol engine to enable maximum efficiency during transition phases, such as acceleration and starts.
The system comprises:
- a compressed-air tank below the boot;
- a low-pressure tank near the rear axle acting as an expansion chamber,
- a hydraulic system consisting of a motor and a pump in the engine bay.
They hydraulic system features bespoke epicyclic transmission to strike the right balance between the two different energy sources. This replaces the manual transmission to enable automatic shifting.
The two tanks are found at the rear of the vehicle, consisting of an aluminium core to ensure watertightness, covered in a composite skin to add strength.
The monitoring system will select the mode that offers the greatest efficiency for the driving conditions encountered, displaying all information to the driver.
In Air (ZEV) mode, the car runs on compressed air alone. This method of driving does not consume fuel and gives off no CO2 emissions, making it ideal for urban environments. In Petrol mode, the car is powered only by the petrol engine. This is more suitable for travelling at a steady speed on main roads and motorways. The Combined mode is designed for transition phases in urban environments and on the road, such as standing starts and acceleration. It draws on the two energy sources in proportions adjusted to achieve optimal fuel consumption.
The compressed-air tank is recharged when slowing down (while braking or taking the foot of the pedal) or by use part of the energy developed by the three-cylinder petrol engine to compress the air. Both methods can achieve maximum pressure in just ten seconds.
The latest three-cylinder 1.2-litre PureTech 82 petrol engine ensures optimal performance, especially in reducing loss caused by friction. This represents around 20% of the power used by the engine. To reduce such effects, the two camshafts and pistons are covered in a special Diamond Like Carbon (DLC) coating. The engine oil used in conjunction with new polymer bearings has very low viscosity to quickly reach optimal engine operation. These changes have improved engine efficiency by 4%.
A naturally efficient style
Fluidity is a hallmark of PEUGEOT style; part of its DNA. The 208 has been all about efficiency from the outset and has undergone only a few updates to fine-tune the car's aerodynamics. The 208 HYbrid Air 2L offers a number of improvements to reduce drag. It adopts a lower stance with air intakes that allow just the right amount of air into the engine.
Flow is further improved through the addition of trim to create a seamless transition between the struts and the windscreen. The rear features a tailgate spoiler and an air extractor below the body of the car. This allows the air to flow freely below the car thanks to the efficient underbody fairing.
The wings reveal a camera tucked into a sleek housing that combines style and efficiency in place of the standard mirrors and surrounds. The large-diameter wheels sport aerodynamic hub caps.
The innovative tyre design is another factor contributing to the overall performance. The choice of materials and the tread design allow a combination of slim width and large diameter. All of this helps to improve the aerodynamics and the rolling resistance of the tyres.
Other design benefits include: improved absorption when driving over uneven surfaces, better resistance to aquaplaning and more effective soundproofing. The resulting SCx is a real breakthrough! Engineers and stylists achieved improvements of over 20% without compromising on cabin or boot space!
An automotive industry initiative
In France, the automotive industry provides 800,000 direct jobs through with a range of employers including manufacturers, subcontractors, equipment suppliers, distributors, dealers and service providers. The French government is keenly aware of the strategic importance of the industry to the national economy, and has taken steps to set up a Plate-Forme Automobile (PFA).
The PFA is tasked with drawing up a clear outlook for medium- and long-term challenges across the entire industry and organising relevant initiatives in response to these issues.
The 208 HYbrid Air 2L technology demonstrator is part of this campaign, developed with the help of a number of PFA partners including Faurecia, Michelin, Plastic Omnium and Valeo.