One of the reasons hybrids get good gas mileage is that they allow engineers to use a smaller engine without losing too much performance. The Camry Hybrid, for example, is peppy despite its modest 2.4-liter four-cylinder powerplant. But there are other ways to downsize, and as automakers decide how to meet stricter fuel-efficiency goals, they’re exploring all their options. So it’s no surprise that turbocharged engines are becoming fashionable again.
Turbos work by compressing the air that goes into an engine. Squeezing more air into the cylinder generates more power without making the engine bigger, so a turbocharged V6 may provide as much—or more—power than a conventional V8. But compressing the incoming air, a process car guys call “forced induction,” requires energy. Turbos get that energy from an unlikely source: the car’s exhaust. As hot exhaust gases from the engine race toward the tailpipe, they spin a small impeller that drives the turbo. The result is a little bit like regenerative braking in a hybrid: the turbo recycles some energy that would normally be wasted.
Never driven a turbocharged car? You probably will soon. BMW began turbocharging a few of its mainstream U.S. offerings this year, and other automakers are following suit. General Motors is planning to bring a new turbocharged four-cylinder to the U.S, next year, potentially for use in the Chevrolet Cobalt and Saturn Astra. At 1.4 liters, the engine would be the smallest engine G.M. has offered here in almost 15 years.
Ford has also announced plans to offer turbocharged engines. Ford’s “EcoBoost” technology—a combination of direct injection and turbocharging—yields as much as a 20 percent increase in fuel economy, and is slated to appear on as many as a half-million vehicles during the next five years.
Turbos are a no-brainer for automakers. The technology is mature and cheap—about $250 – $500 per vehicle. And it’s relatively easy to integrate into existing powertrains. That means that during the next few years, we’re likely to see more turbocharged engines than hybrid powertrains. Overall, that should mean our cars use less fuel, which is a good thing. But it remains to be seen whether automakers will view near-term technologies like turbocharging as “good enough” to meet new fuel economy regulations, or whether they will remain committed to investing in longer-term options like hybrids, plug-in hybrids and range-extended electric vehicles that yield much greater fuel savings.