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FEATURE A D V A N C E D M A T E R I A L S & P R O C E S S E S | S E P T E M B E R 2 0 1 8 4 1 ble. Therefore, a new generation of engines, transmissions, and hybrid technology will likely need to play a major role. However, electric and hybrid vehicles have not impressed the American consumer to date. improve fuel mileage for automobiles in the wake of the Mid- dle East oil crisis of 1970. As time passed, political pressures also mandated the reduction of greenhouse gases (GHGs) such as CO 2 and NOx (nitrogen oxides). EXISTING MODIFICATIONS Attempts to reduce fuel consumption were adopted over the decades, including decreasing the number of cylin- ders to reduce engine block mass. Probably the most signif- icant and successful solution to date (and perhaps the most cost effective) has been the integration of turbochargers to four and six-cylinder gasoline and diesel engines combined with six, seven, eight, and even nine and 10-speed transmis- sions. This approach also has limits, especially as fuel econ- omy standards are applied to larger passenger vehicles and half-ton pickup trucks. Where light trucks are concerned, one OEM substituted aluminum for steel body panels with a reported weight sav- ings of 500 to 700 lb (227 to 318 kg). However, body panels are just one of many components that are candidates for po- tential weight reduction, including suspension parts, trans- mission and transfer cases, and structural and space frame components, some of which will be fabrications, castings, and forgings. In every case, the tradeoff between mass and strength must be considered, as well as the potential for re- ducing post-heat treat processing. MATERIALS AND PROCESSING Six materials with suitable strength-to-weight ratios used in automotive construction today include magnesium, carbon composites, cast gray and ductile irons, aluminum, and steel. Each material is used for a specific performance characteristic: Magnesium has been slowly gaining acceptance for use in automotive applications. Its low density and machinabil- ity makes it an ideal candidate for transmission, differential, and transfer cases. However, it lacks aluminum’s overall strength, making it unsuitable for engine blocks and similar- ly stressed applications. It also requires a protective coating to reduce corrosion, whereas aluminum has very good oxi- dation resistance. Probably the biggest advantage of mag- nesium is its availability, although it is not inexpensive to re- fine. It is not found in the pure state, but can be refined from several materials including dolomite and magnesite ore, sea water, and salt brines, which contain about 10%magnesium chloride. Ocean water contains about 0.13%magnesium [2] . Carbon fiber reinforced polymer (CFRP) has one of the most advantageous strength-to-weight ratios of any engi- neered material. However, it is not as easily recycled as alu- minum and wrought and cast ferrous alloys, and there has been much research to make recycling more cost effective. Most virgin woven poly fiber is produced in Japan and is 2016 VEHICLE SALES IN U.S. AND EUROPE Best-selling cars in Europe, 2016: • VW Golf 491,681 • Renault (Clio) 310,944 • VW Polo 307,462 • Ford Fiesta 298,999 Best-selling vehicles in the U.S., 2016: • Ford F-Series 820,799 (half-ton pickup truck) • Chevrolet Silverado 574,876 (half-ton pickup truck) • Dodge RAM Trucks 489,418 (half-ton pickup truck) • Toyota Camry 388,616 • Honda Civic 366,927 • Toyota Corolla 360,483 • Honda CR-V 357,335 (crossover SUV) • Toyota RAV4 352,139 (crossover SUV) COUNTRIES ADOPT AUTOMOBILE FUEL STANDARDS A decade ago, the EU entered into a series of voluntary agreements known as the European Union Automotive Fuel Economy Policy with associations of automobile manufac- turers that sell vehicles in the European market to reduce CO 2 tailpipe emissions. These agreements applied to each manufacturer’s new vehicle fleet and set an industrywide target of 140 g CO 2 /km (100 km per 6 L or 39 mpg). The orig- inal agreement with the European Automobile Manufac- turers Association (ACEA) had an initial compliance date of 2008, while the Asian manufacturers (represented by South Korean and Japanese associations KAMA and JAMA) had to comply by 2009. However, automakers didnotmeet the voluntary target and the European Commission (EC) has now set mandatory targets. In June 2007, the Council of Environment Ministers formally adopted a resolution to approve the shift to man- datory standards and an integrated approach to achieve 120 g CO 2 /km (100 km per 5.2 L or 45.6 mpg), with automak- ers achieving 130 g CO 2 /km (100 km per 5.6 L or 42 mpg) through technical improvements and the remaining 10 g CO 2 /km coming from complementary measures. The full EC strategy to reduce CO 2 emissions from cars and vans is avail- able online, as is the regulation [ 1] . In the U.S., the CAFE (corporate average fuel economy) standardwas adopted in 1975, andwas primarily targeted to 9