There are people who see the rising corporate average fuel economy (CAFE) standards -- 54.5 miles per gallon (23.2 kilometers per liter) by 2025 -- as bad news. They bemoan the death of the big engines, the V-8s that delivered lots of power and sucked up a lot of gas. They say that driving won't be fun anymore, that we'll all be forced to buy dull cars with high fuel economy scores. Booooring, these people say.
Then there are others who have known the CAFE standards would have to rise, given the price of oil, U.S. dependency on foreign oil and the effects of engine emissions on climate change. They saw the higher fuel economy requirements as a challenge, and they began to work on new technologies that would be good for the planet, good for our wallets and still cool. These people are called engineers.
Here are five engine technologies available today or in the very near future, at a variety of price points. These examples -- and there are more like them being invented every day -- promise that the future of driving will still be fun, whether it's in a tiny city car with a direct-injected engine or a supercar with a "push to pass" hybrid booster button.
One way to improve performance and fuel economy is to increase the compression ratio inside the engine. The compression ratio refers to the amount of fuel and air squeezed into the combustion chamber. When this ratio is higher, it uses fuel more efficiently.
Mazda is using this approach to its latest generation of vehicles, both diesel- and gasoline-powered. The SKYACTIV-G gasoline engine, for example, uses a 13:1 compression ratio in North America, where the norm is 10:1. SKYACTIV-G vehicles in Europe have a 14:1 ratio, since more people in Europe use high-octane gasoline regularly.
The problem with higher compression ratios is usually a knocking sound in the engine, which occurs when temperature and pressure are too high in the chamber and the air and fuel mixture ignites too early. Higher octane gas on its own can solve some of this problem, but Mazda has developed a longer exhaust manifold that reduces the temperature and the chance of engine knock. The SKYACTIV-G system also has a faster combustion time, which means the air-fuel mixture ignites properly before the temperature can build up and knocking begins.
All this engine technology -- as well as weight-saving materials and a new transmission -- mean 15 percent lower fuel consumption and emissions and 15 percent more torque. And increased torque translates into more driving fun.
Most of the engines on the road today mix the fuel and air before introducing them to the combustion chamber. In a direct-injected engine, highly pressurized fuel is squirted directly into the combustion chamber at the top of the piston's stroke, near the spark plug.
Since this creates quite a bit of pressure in the combustion chamber, direct injection can cause knocking, too, just like higher compression ratios. Ford Motor Company has solved this problem by combining direct injection with turbo charging, which uses exhaust gases to boost performance.
By bringing these two proven technologies together, Ford has built engines that are more powerful than their predecessors, even though they're smaller and use less fuel. Ford calls these engines EcoBoost.
The 2011 Ford F-Series shows how EcoBoost keeps driving from being dull. You could buy the Super Duty with its optional 6.8-liter V-10 with 362 horsepower and 457 lb-ft of torque -- plenty for work or play. Or you could buy the F-150 with the EcoBoost 3.5-liter engine with 365 horsepower and 420 lb-ft of torque -- and that's in a smaller, lighter truck. That kind of horsepower per pound ratio is going to deliver lots of fun with fewer fill-ups.
This technology, which allows a driver to choose between regular gasoline or an ethanol blend, has been around for a while. Ethanol blends are designated by the letter E followed by a number; E85 means the fuel is 85 percent ethanol and 15 percent gasoline. The Flex Fuel badge usually means the vehicle can use up to E85, as well as lower-percentage blends like E10.
Often, you'll find that Flex Fuel vehicles are big trucks and SUVs that drink fuel like a fish drinks water. Ethanol has a higher octane rating, but you get fewer miles per gallon when using it. On the plus side, ethanol can be made from biological sources.
But for expensive performance cars, that's the perfect mix. Bentley Motors is working to make its entire fleet of cars Flex Fuel-capable, beginning with the Bentley Continental SuperSports, the fastest Bentley ever built.
The engineers at Swedish supercar company Koenigsegg used ethanol to boost both power and green credentials. The company's very limited edition CCXR model had an 806 horsepower engine -- when it was powered by gasoline. But fill the tank with higher-octane ethanol, and the engine could crank out an amazing 1,018 horsepower.
Over the past decade and more, electric-gasoline hybrid systems have become commonplace. There isn't a city in America that doesn't have a Toyota Prius, Ford Escape, or any other hybrid tooling around its streets. The technology works, the batteries last and the gas mileage is some of the best in the world.
But the fun factor for many hybrids is admittedly low. Jaguar is set to remedy that, with its "push to pass" button in the C-X16 concept shown at the 2011 Frankfurt Motor Show. It's powered by a supercharged 3-liter V-6 gasoline engine and an electric motor, just as most hybrids are.
The difference is in the "push to pass" button on the steering wheel. Pressing this accesses the electric motor for a 70 horsepower boost, much like the KERS system used in Formula 1 racing. Put it all together, and the Jaguar C-X16 can go 186 miles per hour (299.3 kilometers per hour) and reach 60 miles per hour (96.6 kilometers per hour) from a standstill in less than four and a half seconds.
This type of engine only uses the cylinders it needs, when it needs them. For example, when the Audi S8 is accelerating from 0 to 62 miles per hour (100 kilometers per hour) in 4.2 seconds, it requires all eight of its cylinders to be firing.
But when it reaches cruising speed a few seconds later, it no longer has that heavy workload to maintain. Four of those eight cylinders cut out completely, so the engine acts like a four-cylinder. If you need to pass, the other four cylinders kick in again, and then cut out when the car's speed is steady again. This technology improves fuel efficiency by about 10 percent when cruising along at speed.
Audi also uses an active noise control system to keep the sound of the engine and exhaust consistent and active engine mounts so passengers won't notice when the cylinders cut out or fire up. All told, the new V-8 engine has more power than the V-10 it replaced -- and it gets better gas mileage.
For more information about new engine technologies and other related topics, follow the links on the next page.
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- Audi. "The Audi S8: At a Glance." Audi Media. Oct. 9, 2011. (Nov. 30, 2011) http://www.audiusanews.com/pressrelease/2619/132/audi-s8-glance
- Audi. "The new Audi S8 for 2013 Model Year." Audi Media. Oct. 20, 2011. (Dec. 7, 2011) http://www.audiusanews.com/newsrelease.do?id=2662&mid=1
- Del-Colle, Andrew. "Obama Announces 54.5 mpg CAFE standard by 2025." Popular Mechanics. July 29, 2011. (Dec. 7, 2011) http://www.popularmechanics.com/cars/news/fuel-economy/obama-announces-54-6-mpg-cafe-standard-by-2025
- Ford. "Ford Engines Are Getting Smaller While Fuel Economy and Horsepower Are Growing." Media.Ford.com. March 23, 2011. (Dec. 7, 2011) http://media.ford.com/article_display.cfm?article_id=34272
- MotorTrader. "Ford EcoBoost Technology: More with Less." MotorTrader.com. June 9, 2011. (Nov. 30, 2011) http://www.motortrader.com.my/Cars/NewsHeader/News-in-2011/Features/Ford-EcoBoost-Engine-Technology.aspx
- Mazda. "SKYACTIV Technology Workshop 2011 Press Kit." (Nov. 30, 2011)
- Stenquist, Paul. "Turning Up the Pressure to Keep Gas in the Game." The New York Times. Nov. 11, 2011. (Nov. 30, 2011) http://www.nytimes.com/2011/11/13/automobiles/turning-up-the-pressure-to-keep-gas-in-the-game.html