Getting 35 MPG

Most of the technology auto manufacturers need to make the mandated 35 miles per gallon Corporate Average Fuel Economy (CAFÉ) standard ordered by 2020 not only exists, but also is already in use in some vehicles, says Charles Hubbard of Lexus College.

Electronically-Controlled VVT
Among the top features already in use that will notably increase fuel mileage is electronically controlled variable valve timing, said Hubbard. Compared to the more common hydraulically controlled variable valve timing, electronically controlled camshafts can more quickly and more precisely alter timing for better fuel economy. In addition to providing great fuel economy, electronically controlled variable valve timing still offers plenty of power for passing and merging onto fast-moving freeways. Non-variable cams will soon join carburetors as automotive relics.

Direct Fuel Injection
Another fuel saver is direct fuel injection. Current fuel injectors spray fuel above the intake valve. That’s better than a carburetor but not as efficient as direct injection, which squirts fuel directly into the cylinder at pressures ranging from 600 to 2200 pounds per square inch. This allows the engine to inject fuel at either the bottom or top of the compression stroke, depending on the need, said Hubbard. Direct injection would be especially helpful during cold starts when fuel normally collects along the cylinder wall and doesn’t combust fully. Such direct injection systems would also employ conventional port fuel injection in an effort to get the most from every spritz of fuel.

Insulated Tank
Another feature that gives better fuel economy is a vacuum-bottle-like insulated tank used to store warm coolant. Now in use on the Toyota Prius, this allows the engine to warm up faster and, thus, produce less cold-start emissions and use less fuel. During cold starts, an engine uses much more fuel than when it is up to temperature.

Roll-Resistant Tires
Lower rolling-resistance tires, which require less energy to get moving and keep rolling, are now in use. Improvements are easily achievable, but the increases in mileage will be small, no more than a couple of miles per gallon. However, there’s no free lunch with this fuel-saving measure: Low rolling-resistance tires have less grip—wet or dry—than conventional tires. Racecar tires have very high rolling resistance, but great traction.