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This latest Tucson got a major fuel economy bump by simply downsizing, going from an aged 2.7-litre V-6 to a smaller and more efficient new 2.4-litre four-cylinder. (Hyundai/Hyundai)
This latest Tucson got a major fuel economy bump by simply downsizing, going from an aged 2.7-litre V-6 to a smaller and more efficient new 2.4-litre four-cylinder. (Hyundai/Hyundai)


How car makers are wringing out gains in efficiency Add to ...

Car companies are racing ahead with plans to deliver fleets of vehicles that meet CAFE standards.

To guide them, they’re looking to reduce fuel consumption by attacking places where the most energy is lost from burning fuel. According to research from Honda:

  • 60 per cent of energy is lost to engine and exhaust heat
  • 15 to 25 per cent is lost to deceleration and idling
  • 10 to 15 per cent is lost to traction or rolling resistance
  • 5 to 10 per cent is used for the drivetrain and accessories

Thus we’re now seeing auto makers focus on engine efficiencies, while they adopt stop-start systems and electric steering and electrically driven accessories, even as they work with tire companies to reduce rolling resistance where the rubber meets the road.

And cost? Trade Journal Automotive News reports that the book-length U.S. Government report, Assessment of Fuel Economy Technologies for Light Duty Vehicles, prepared by the National Research Council, shows it is going to cost consumers a small fortune to get from the current gasoline engine to the electrically powered vehicles favoured by politicians through regulations and taxpayer funded subsidies.

For mid-sized and large cars:

  • For a 29 per cent increase in fuel economy for a gasoline internal combustion engine, the added costs totals about $2,200 per vehicle;
  • For a 38 per cent improvement in fuel economy, diesel improvements would total about $5,900;
  • For a 44 per cent improvement in fuel economy, hybrid technologies add up to about $6,000.

The numbers suggest that the best short-term solution for meeting CAFE rules is to wring every possible efficiency out of the traditional internal combustion engine – and then move to pairing internal combustion engines with hybrids and plug-in hybrids. This makes sense: gasoline engines use a fuel that is generally inexpensive, plentiful and energy-rich compared to the available alternatives.

So the painstaking task of eliminating waste is in full flight at all the major car companies. Take the latest version of the Hyundai Tucson as an example. Squeezing fuel economy out of a vehicle powered by a conventional gasoline engine is tough slogging. It requires attention to detail and a commitment to grinding little percentages out of everything that has an impact on fuel economy.

“A lot of these things are not sexy or exotic,” says Hyundai Canada vice-president John Vernile, the marketing boss. “Frankly, I can’t advertise this stuff. But they all add up.”

This latest Tucson got a major fuel economy bump by simply downsizing, going from an aged 2.7-litre V-6 to a smaller and more efficient new 2.4-litre four-cylinder. It was not a step backward in horsepower, either: the 2.4-litre is rated at 176 hp, while the 2.7-litre V-6 goes out at 173 hp.

The engine switch gave Hyundai a 12 per cent fuel economy bump. Another 3.6 per cent gain came from lowering the Tucson’s weight by 27.7 kg. Electric power steering improved fuel economy by another 3.5 per cent, too.

Other fuel economy gains:

  • a new exhaust port design (2.0 per cent);
  • silica tires (1.8 per cent);
  • six-speed automatic transmission, from the old four-speed (1.4 per cent);
  • new alternator management system to reduce unnecessary recharging (0.8 per cent);
  • automatic transmission fluid warmer (0.5 per cent).

Auto makers also stand to gain by shedding weight, though they must do so without compromising safety. This is no small task. The basic rules of physics say the heavier the car, the more secure the occupants.

Thus, car companies are not scrimping on safety as they shed weight by moving to:

  • more sophisticated engineering and design architectures;
  • new lightweight materials, such as high-tensile steel;
  • advanced cabin safety technologies;
  • lighter components of any sort that isn’t related to safety.

Mazda’s SkyActiv technology has made weight loss the centrepiece of a suite of fuel-saving technologies that by 2015 aims to boost average fleet fuel economy by 30 per cent above 2008 levels. By trimming about 100 kg from the next generation of each model, Mazda plans to see a 5 per cent increase in fuel economy for each new car.

General Motors has gone a similar route with the most fuel-thrifty version of its Chevrolet Cruze compact, the Eco model. Chevy engineers focused on aerodynamic performance, mass optimization and powertrain enhancements.

  • Aero enhancements: Many were developed and refined in more than 500 hours of wind-tunnel testing of the Chevy Volt, which shares a core architecture with the Cruze. The upper grille has more “closeouts” to improve aerodynamics. A lower front air dam extension, a rear spoiler, a lowered ride height and underbody panels smooth airflow beneath the car. These moves and others reduced aerodynamic drag by 10 per cent over a non-Eco model.
  • Mass optimization: More than 42 changes were made on the Eco to reduce weight. The diet program went right down to including hundreds of weld flanges on the vehicle. They were reduced 1 millimetre to 2 mm in length, which saved several pounds. Lighter wheels and tires are used on the Eco, also.
  • Efficient powertrain: The Cruze Eco is powered by a power-dense Ecotec 1.4-litre turbocharged engine and a standard six-speed manual transmission. The transmission’s gearing is optimized for the model’s specific 17-inch wheel/tire combination and includes aggressive ratios for first and second gear coupled with a highly efficient, “taller” sixth-gear ratio for highway driving. That means engine rpm is reduced on the highway, which in turn reduces fuel consumption.

As the 2016 CAFE deadline approaches, look for every car company to explore and exploit every possible approach to maximizing fuel economy and lowering emissions. Cars and light trucks will get smaller and weigh less.

Also, more and better gasoline-electric hybrids will arrive on the scene, from the latest version of the Toyota Camry Hybrid, to the coming new 2013 Ford Fusion Hybrid and Acura’s ILX compact hybrid. Plug-in hybrids are coming in a big way, too – including a Toyota Prius plug-in and a plug-in version of the Fusion.

Mercedes is going in a familiar direction given the company’s expertise in diesel engines: the E300 BlueTec Hybrid sedan combines a diesel engine (a 201-horsepower four-cylinder) with a 27-horsepower electric motor. Indeed, German manufacturers who for years scorned hybrids are now turning to them, including Audi with an upcoming Q5 and Volkswagen with a Jetta Hybrid that teams a turbocharged 1.4-litre four-cylinder engine with 27-horsepower electric motor.

And then there is the downsizing of engines. Ford has long touted its EcoBoost system, which pairs direct injection with turbocharging to deliver, for instance, six-cylinder power in a four-cylinder engine with fuel economy to match. The coming Cadillac ATS sedan will also use a small four-cylinder with turbocharging and direct fuel injection.

Not to be lost are the more refined transmissions and more advanced engine management systems that together will deliver the kind of performance customers expect and the fuel economy government regulators are demanding.

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