In these days of fluctuating fuel prices and tightening government fuel economy and emissions requirements, some of the most interesting technological developments revolve around the internal combustion engine.
Hybrid cars receive a lot of attention, but while hybrids and electrification will play an important part in our transportation future, automakers know the internal combustion engine isn't going away anytime soon.
Many automakers have found success in using gasoline direct injection. A more precise method of fuel delivery, a high-pressure injector sprays fuel directly into each cylinder. Historically, engines have had the injector upstream of the intake valve. Gasoline direct injection has been around for a long time, but it took combining it with two other technologies, turbocharging and variable valve timing, to fully reap the benefits. Add this to a smaller engine which uses less fuel, and the turbocharger adds the punch American drivers want.
This is the main strategy behind Ford's "EcoBoost" technology, for example. Ford takes advantage of the piston cooling effect of direct injection to raise compression ratios without engine-damaging knocking from pre-ignition, without requiring higher octane fuel; a higher compression ratio means more power and efficiency.
Diesel power is making a comeback, thanks in large part to German automakers. Cars with diesel engines generally get better fuel mileage than gasoline powered cars for a number of reasons, among them the fact that diesel fuel contains more energy than gasoline, and diesel engines run higher compression ratios.
Today's diesels are clean and quiet, having benefited from years of refinement in Europe and other parts of the world where they remained popular. Volkswagen never gave up on diesels in the U.S. market, and now Audi is heavily promoting diesel engines across their luxury portfolio. BMW has increased offerings, and the builder of the first-ever diesel powered passenger car, Mercedes-Benz, has made the base engine for the 2014 E-Class a diesel, among other choices. But even Chevrolet has jumped in the game with the Cruze Turbo Diesel, introduced at last year's Chicago Auto Show and on sale now.
The majority of heavy duty truck customers prefer diesel, but some new light duty truck diesels are debuting. The 2014 Ram 1500 pickup is available with the 3.0-liter EcoDiesel V-6, which also is offered in the 2014 Jeep Grand Cherokee. Nissan recently announced a Cummins Diesel V-8 for the next generation Titan pickup. General Motors is holding off on a diesel for 1500 pickups, but said a 2.8-liter diesel will be an option for the 2015 GMC Canyon midsize pickup.
Consumers will also notice an increasing number of multi-gear transmissions. Several automakers are using eight and even nine-speed automatics to keep engines running at their most powerful and efficient speed. Another type, called dual-clutch transmissions, operates automatically, but mechanically are like two manual transmissions side-by-side. They are able to shift faster than traditional automatics, and thereby waste less energy. However, some American drivers are reportedly having trouble accepting their slightly different behavior.
Between the engine and transmission another technology is gaining wider use is automatic stop/start. As the name implies, the engine automatically shuts off when you bring the vehicle to a stop. Extra battery power allows the accessories to run for a period of time. Then when you take your foot off the brake, the engine restarts.
But it's not just about the engine and transmission anymore. The entire vehicle needs to be optimized for better mileage. Mazda has been successfully using a holistic approach with its Skyactiv technology.
"Basically it means they tore down the whole car and looked at every part in order to get better fuel economy," said Andrew Thompson, sales manager at Kennedy Mazda. "They make it lighter through the use of high-tensile steel, which is also stronger, then put in their best, smoothest-running engine. Mazda has some very informative YouTube videos that explain it all."