F & S report: Shedding the extra pounds

The 'Go Green' mantra is urging the world to work towards an eco-friendly environment. The current environmental issues add pressure on automakers to manufacture fuel-efficient cars with lesser CO2 emissions. In a bid to meet this challenge, OEMs are focussing on research and technology to develop lighter cars and are using weight reduction as a key strategy to develop fuel-efficient vehicles. A 100kg weight reduction in a car can yield a two to three percent increase in fuel economy and 3.5 grams per km emission reduction of CO2. Most OEMs have set a target to reduce the weight of the vehicles by 10 to 15 percent by 2015, across their fleets.

It has become a nightmare for OEMs to manufacture more fuel-efficient vehicles without compromising their performance, and at the same time comply with stringent CO2 emission and fuel economy standards. On the other hand, the trend of shifting from gas guzzlers to fuel sippers continues, as customers have become more eco-conscious. This is evident from the 25 percent drop in the sales of sports utility vehicles and pickup vehicles in North America.

Technologies to shape the muscle The unveiling of a revolutionary new micro car, codenamed the T25, by Gordon Murray Design of the UK is generating a lot of interest. Reductions in size and weight on the T25 are achieved though innovative design and the use of ultra-light weight materials, which also resulted in its low cost. The result is a car which weighs 400kg less than most small cars, yet feels like one much larger and comfortable to drive.

Weight reduction is sought in three different ways – by the use of lightweight materials, by optimising the design of different components and system layouts, or by innovations in manufacturing process. However, the key challenge is to keep an optimum balance between cost, weight and performance, to comply with regulations as well as satisfy the customers. Powertrain, chassis and exterior system account for more than 50 percent of the total weight of a car. This is the target focus area of weight reduction for every OEM. Reduction in the weight of the powertrain and vehicle structure can subsequently reduce the weight of the chassis, brakes and gears, resulting in reduction in vehicle weight.

The realisation of weight reduction in powertrain is all about optimisation – for example engine downsizing with turbocharging. Engine downsizing of 30 percent on an average reduces 10 to 15 percent of the total weight of the engine and reduces 10 to 20 percent CO2 emissions. Fiat has downsized its four-cylinder (1.4 litres) engine to a 2-cylinder (0.9 litres) engine to achieve 20 percent reduction in weight. This is one of the key powertrain trends also followed by Ford, Nissan, Toyota and General Motors. A recent Frost & Sullivan customer study shows that over 70 percent of consumers will consider buying a downsized engine if it can provide greater fuel efficiency while maintaining performance. Vehicle performance is achieved by turbocharging, which increases the total weight marginally, when compared to the mass already lost. Weight reduction in chassis and exteriors is mainly achieved by using lightweight materials like aluminium, magnesium, titanium and plastics, used in a cost-effective manner.

The multi-material concept for the Body In White (BIW) is a new trend targeted at reducing weight. The Super-Light Car consortium, co-founded by the European Commission consisting of 38 leading organisations worked on a multi-material BIW concept aimed at reducing around 41 percent of the weight of the car. The key highlights were longitudinal rail in HSS, tailored welded blanks, strut tower in magnesium die-cast, floor panel in aluminium and magnesium blank, wheelhouse and rear longitudinal rail in aluminium-blank and roof in magnesium blank.

There is a clear trend of the use of alternative lightweight materials to become a key element in the design of future cars, as it offers a five percent reduction in the total vehicle weight. Material substitution depends on the mechanical properties, cost, design and manufacturing capabilities. We foresee a trend of increase in the use of aluminium and plastic content in vehicles by 2015. Usage of medium and conventional high strength steel will also increase by 2015. The usage of composites is common in high-end luxury cars like Mercedes-Benz and Audi, resulting in higher weight reduction.

Vehicle manufacturers to go on a diet European and Asian OEMs have more experience in manufacturing fuel-efficient vehicles as they need to comply with fuel economy standards and emission regulations. However, American OEMs, for whom stringent fuel economy standards have just been introduced, will find it more challenging to shift from larger gas guzzlers to fuel sippers and to convince customers to buy smaller cars. Although American companies can adopt certain successful European and Asian OEM strategies in the short term, it is important to develop technologies for long-term sustainable future. Nissan, as a promising green initiative, has set a strict deadline to reduce average weight of its vehicles by 15 percent over seven years, compared to its 2005 line-up. The 15 percent cut in weight can yield an average reduction of a 10 percent drop in fuel consumption. Nissan is taking it on a phased manner by building and trying technologies on low-volume models like the Nissan Skyline GTR, and then cascading it to the mass production models based on the application suitability.

The manufacturer has various approaches towards weight reduction, such as rethinking the vehicle design, BIW, integration of functions, engine downsizing combined with turbochargers and use of various lightweight materials. On the same lines, Toyota has also set a goal to reduce 10 percent of weight on its mid-size vehicles. As an initiative to reduce CO2 emissions, the manufacturer is reconsidering everything from vehicle specifications, performance and use of lightweight materials. Its 500cc plug-in concept, the 1/X, houses an ultra-lightweight hybrid powertrain that combines a rechargeable lithium ion battery and a flexible fuel engine. This makes the car weigh only one-fourth of the total weight of a Prius' powertrain system. The four-seater concept model weighs around 420kg, which is one-third the Prius’ kerb weight. On the other side of the Atlantic, the Big Three, once known to be the makers of the worlds’ best gas guzzlers, are currently under much pressure to adhere to eco protocol and fuel crisis. As a core weight reduction strategy, Ford has set a target of reducing 113kg to 340 kg on all its vehicles by 2020, as a part of its plan to improve fuel economy by 40 percent by 2020. Using smaller displacement engines, uni-body applications, lightweight application and electric power steering are the key focus areas in the future. General Motors is actively exploring the use of lightweight materials to reduce vehicle weight, particularly plastics and composite materials. The Chevrolet Volt from the GM stable uses resins and composite materials. The use of composites on the fender, window glazing, instrument panel and steering wheel itself contribute to weight reduction of 30 to 50 percent per part.

Looking forward to a lighter ride Sustainability and lightweight are the current buzz words in the automotive world to create a green future. From the recent Frost & Sullivan’s end-user survey on 'European Consumers’ Attitudes & Perceptions towards Sustainability, Environment and Alternate Powertrain', it is clear that 36 percent of customers consider CO2 as the most harmful vehicle emission. About 50 percent of the respondents said that they would use fuel consumption, CO2 and total life emission to determine how environmentally friendly or sustainable a vehicle is, thus defining vehicle purchase behaviour.

With manufacturers bracing up to develop greener vehicles, the million-dollar question is about affordability and the trade-off between weight and the cost. How much will each manufacturer be ready to pay for the related cost? The changes in the market dynamics with the increasing raw material cost pose a major challenge to the manufacturers. At the end of the day, manufacturers have to do some firefighting to balance weight and cost. While manufacturers are reactive in environmental measures, it is important to become proactive in development of lightweight concepts in the future. Although weight reduction at present focuses on the usage of lightweight materials and designing at a very affordable cost, it is critical to involve expert engineering to look out for new systems and breakthrough designs.