A look at how cars are squeezing more miles from gas

The Toyota Prius and other fuel sippers are rolling platforms for many innovative ways of improving fuel economy.
The Toyota Prius and other fuel sippers are rolling platforms for many innovative ways of improving fuel economy.
Posted: September 10, 2012

Thanks to gasoline's toe-to-toe dancing with $4 a gallon, surveys show that prospective auto buyers are assigning a higher and higher priority to fuel economy.

At the same time, government concerns about national security, pollution, and climate change have mandated ever-increasing Corporate Average Fuel Economy (CAFE) mileage standards.

The result is a lot of pressure on automakers to squeeze more work out of a gallon of gas and/or find alternatives to its use. Some of those efforts, such as hybrids and electrics, are quite familiar to all of us. Others, such as electric steering and transmission-heat management, may not be.

So, why don't we take a quick look at some of the ingenious ways automotive engineers have been getting more bounce to the ounce of petrol:

Hybrids and electrics. Hybrids cut fuel consumption dramatically by letting an electric motor and battery share the vehicle-powering duties with a gas engine. Pure electrics, such as the Nissan Leaf and Ford's soon-to-be-released electric, use no gas at all, but have range limitations. That range problem is not true of the Chevrolet Volt, which uses a gas engine not to power the car but to recharge its battery if it gets too low.

Direct injection. Instead of injecting fuel into the port behind the intake valve, as conventional port injection does, direct injection sprays the fuel directly into precisely the right spot in the combustion chamber for optimum burning. That in itself increases power. Also, as Richard Truett, Ford power train spokesman, points out: The directed-injected fuel is cooler than a port charge would be, and the resultant combustion-chamber cooling permits a higher compression ratio, which, in turn, means more power.

In addition to more power, direct injection boosts fuel economy. Ford, which uses direct injection in its EcoBoost engines, estimates savings of up to 20 percent. That savings is realized simply because the extra power allows you to maintain the same speed with less gas pedal. It really is a win-win situation. The only reason it isn't more widely employed is that it adds a couple hundred bucks to manufacturing costs.

Automatic transmission upgrades. Improvements have typically left automatics with fuel economy as good as or better than manuals. Employing more gears has meant that power requirements can be more closely matched to the engine's "sweet spot," which is the r.p.m. range that allows maximum fuel economy.

Engineers have also been able to get the automatic's torque converter to lock up sooner, thus decreasing gas-wasting slippage. Another innovation is transmission-heat management, which raises fluid temperatures enough to significantly reduce viscosity - and thus increase efficiency. Mike Raymond, the lead engineer on the 2013 Ram pickup, told me this wrinkle produced a 1.7 percent increase in mileage.

Electric power steering. This innovation, which has taken autodom by storm, uses an electric motor to provide steering assist rather than the traditional hydraulic pump. The latter hurts gas mileage because it is actuated by engine power. Employing the electric unit on the new Ram prompted a 1.8 percent mileage boost, according to Raymond.

Start-stop technology. This clever gizmo shuts off the engine when you come to a stop, then starts it as soon as you take your foot off the brake. Ford claims a 10 percent fuel saving in city driving.

Low-rolling-resistance tires. The low-resistance design means less friction, and that translates into better mileage. These tires are no longer the province of gas-sippers like the Toyota Prius. They'll be standard on the new Ram pickup. (Tire-monitoring systems also help mileage by telling you when your tires are underinflated - and thus wasting gas.)

High-strength steel and aluminum. High-strength steel can save weight - and hence, fuel - because you don't need as much to meet a strength requirement. Thus, engineers were able to take 30 pounds out of the new Ram's frame by using high-strength steel. Making the hood out of aluminum saved an additional 26.


Contact Al Haas at alhaasauto@aol.com.

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