The 2017 GMC Acadia sport utility vehicle that is just starting to arrive in dealerships around the country is 700 pounds lighter than the version it replaces and can go 23 miles on a gallon of gasoline, up from 18 mpg, a 28 per cent improvement.
One of the secrets to the big weight loss? Glue.
Many of the steel parts of the Acadia’s underbody are held together not by rivets or welds but by advanced adhesives similar to those used in modern airplanes like the Boeing Dreamliner. Since the glue bonds parts together all along the seam where they connect, not just in certain spots, the parts become stiffer. Because of the stiffness, General Motors is able in many cases to switch to thinner steel, helping the new Acadia shed pounds.
The grades of steel are thinner by only about the width of a human hair, but “it’s all the little things that add up to the big number,” said Charlie Klein, executive director of GM’s global carbon-emissions reduction strategy.
Automakers are racing to improve fuel efficiency to meet the increasing mileage standards that environmental regulators have set for the next nine years. Space-age adhesives are being used more widely, just one of the many leaps manufacturers are taking to reduce weight and save fuel.
But to continue their gains, automakers must find additional innovations. One promising technology on the horizon is a new type of gas-electric hybrid that draws power from a 48-volt battery, which is more powerful than a standard 12-volt auto battery but less expensive and less complicated than the power packs of 200 volts or more found in hybrids like the Toyota Prius.
The 48-volt battery drives an electric motor that gives the engine an extra 20 or so horsepower, cutting fuel use in starts and acceleration.
Mary Gustanski, vice president of engineering and programme management at Delphi, an auto supplier that is going to produce 48-volt systems for car companies, believes these hybrids can improve the fuel economy of normal gasoline-powered cars by 15 per cent or more with little additional cost. “Is it leaps and bounds?” she said. “No, but does it move us further along? Definitely.”
Hyundai Motor, the Korean automaker, is “working very hard on 48-volt technology,” said Michael O’Brien, the company’s vice president of corporate and product planning. He declined to say when those cars would be on the market. GM also expects to offer 48-volt cars in the United States market in the next few years, an executive said.
Gustanski said Delphi’s technology would first appear in Europe and China in 2018. Continental, another supplier, plans to begin producing 48-volt systems for automakers by the end of this year.
Even with new technologies, automakers still have a steep uphill climb to keep pace with gas-mileage targets. By 2025, they are supposed to sell a fleet of vehicles that hits an average of 54.5 mpg.
That number is based on a complicated formula that gives credits for reducing emissions from air-conditioners and selling electric vehicles, among other things. In real-world driving, the target equals a fleet average of about 40 mpg. The average for cars and light trucks that were sold in July was 25.4 mpg, according to the University of Michigan Transportation Research Institute.
Last month, a joint report from the Environmental Protection Agency and the Transportation Department said automakers were probably able to reach only an average rating of about 50 mpg by 2025 — about 36 mpg in real-world situations.
The main problem is that low gasoline prices and the absence of high fuel taxes that are common in most other advanced industrial nations have enticed Americans to move away from cars and buy more pickup trucks and SUVs, which score lower on fuel efficiency.
Missing the 2025 target would result in higher levels of carbon dioxide emissions, which regulators are trying to reduce in a bid to battle climate change.
Regulators have just begun a review of the fuel-efficiency standards and by April 2018 must decide whether to ease them in some ways — a path automakers would prefer — or leave them unchanged.
Automakers and regulators are at odds. At an industry conference in Michigan this month, the EPA’s director for air quality, Christopher Grundler, shrugged off suggestions that the 2025 target should be lowered. He said the standards were “working spectacularly” and noted that carmakers had made good progress and already offered many models that met the 2025 level.
These include hybrid and plug-in models from Ford Motor, Hyundai, Toyota and others, as well as pure electric vehicles like Tesla models and GM’s Chevrolet Bolt. Ford’s aluminium-bodied F-150 pickup truck, when equipped with the company’s EcoBoost V-6 engine, comes close to the 2025 requirement — 23 mpg in real-world driving — for vehicles of that size.
Automakers agree that electric cars offer impressive fuel-economy numbers but counter that consumers buy too few of them to move the average number. The big challenge, they say, is in improving fuel-economy in conventional gasoline-powered cars without adding so much cost that consumers turn away.
“It is going to be extremely difficult for traditional powertrains to hit those targets in the last couple of years” leading to 2025, said Richard L. Gezelle, a senior programme manager at Toyota.
Toyota is one automaker that has less interest in 48-volt “mild” hybrids, as they are known in the industry. Gezelle said his company thought automakers would need to focus more on breakthrough technologies — such as electric cars and hydrogen-powered fuel cell vehicles — that can meet the 2025 standard and continue improving fuel efficiency beyond then.
For now, automakers are making gains from a series of technologies they started introducing about six years ago. These include shrinking the size of engines while adding turbocharging, which increases power and efficiency by forcing extra air into an engine. This approach enables a four-cylinder engine to put out about the same power as a traditional V-6, and a V-6 to replace a V-8.
At the same time, automakers are hoping for advancements from a new wave of innovations. They include:
— Stop/Start
This system shuts off the engine when a car stops at a light or in traffic. Some vehicles already have this feature, but their rough restarts have turned off many consumers. Hybrids with 48-volt systems promise improvements.
— Freewheeling
Also known as engine-off coasting, this lets an engine shut off momentarily while a car is coasting, reducing fuel consumption. A hybrid car can use its electric motor to maintain cruising speed, letting the engine remain off longer.
— New Materials
Automakers already use more aluminium and advanced, lightweight steel. Now magnesium, which is a third lighter than aluminium, is appearing more frequently. Fiat Chrysler is using the metal in the tailgate of the 2017 Chrysler Pacifica minivan.
— Cylinder Deactivation
For years engines have had the ability to shut off two or four cylinders to conserve fuel. Using new computer algorithms, Delphi, GM and Tula, a Silicon Valley tech company, are working on “dynamic skip fire,” a way of turning individual cylinders on and off as needed
Source: themalaymailonline.com
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