There are many technologies and techniques currently available that can significantly increase fuel efficiency, thus saving consumers money and reducing greenhouse gas emissions and other pollutants Many technologies, like turbo charging and direct fuel injection, are more readily associated with vehicle performance, but they also provide significant improvements in fuel economy. In December 2007, Congress increased Corporate Average Fuel Economy (CAFE) standards with the Energy Independence and Security Act of 2007 (EISA, P.L. 110-140), which requires cars and light trucks to achieve an average of 35 miles per gallon by the year 2020. In addition, federal loans provided to General Motors and Chrysler in 2008 and 2009 were conditioned, in part, on those automakers making new investments in fuel efficiency. Some vehicle efficiency strategies are listed below.

Drive Train Efficiency

Continuously Variable Transmission
These transmissions do not have a fixed number of gears. Instead, they employ a pair of variable diameter pulleys which are linked by chain or belt, creating an infinite amount of gear ratios between a pre-set minimum and maximum. This continuous variability limits the amount of revolutions per minute for any given speed and, therefore, reduces fuel consumption.

Cylinder Deactivation
Vehicles equipped with this technology have the ability to deactivate half of their engine’s cylinders while cruising and reactivate them under heavy acceleration. Engines with six or more cylinders can use this technology without a noticeable drop in performance.

Direct Fuel Injection
In traditional engines, fuel and air are mixed outside the cylinder. In engines equipped with direct fuel injection, fuel is injected directly into the barrel of the cylinder, allowing for greater control of the fuel air mixture and more efficient combustion.

Integrated Starter/Generator
This technology allows engines to be shut down instead of idling for short stops, such as red lights, and instantaneously restarted under acceleration.

Turbocharging and Supercharging
Turbochargers are fans powered by engine exhaust that force compressed air into the engine cylinders. Similarly, superchargers use fans to force compressed air into the cylinders, but they are powered by the engine itself. The compressed air improves combustion efficiency by allowing more fuel to be burned per piston stroke. Engines equipped with either of these technologies produce more power and use less fuel than engines of the same size without them.

Variable Valve Timing and Lift
Valves control the flow of fuel and air into, and the flow of exhaust out of the cylinders in the engine. In traditional vehicles, the distance a valve travels remains constant at all speeds. Variable valve timing and lift allows the distance the valves travel to change in accordance with the speed of the engine.

Aerodynamic Efficiency and Weight Reduction

Lighter Materials
Using carbon fiber and lighter metals, manufacturers have managed to reduce the weight of cars while maintaining durability and strength. Engines in lighter vehicles operate more efficiently than engines of the same size in heavier vehicles.

Ride Height
Vehicles that ride low on their wheels are exposed to less drag than ones that do not. Since the gap between the bottom of the car and the road is smaller, less air is exposed to the rough underside of the vehicle and the bottom of the tire tread. Adding or repairing an existing broken air dam (a metal or plastic device fitted below the front bumper designed to deflect air away from the bottom of the car) can reduce drag and increase fuel mileage.

Vortex Generators
These small, delta-shaped devices can be placed on the roof of a vehicle, just in front of the rear window. The aerodynamic shape of the generators creates vortices that reduce drag by causing the air to flow along the rearward surfaces of the car, such as the rear windshield and trunk lid, instead of flowing above them. They lessen net drag by reducing the area of separated air flow behind a vehicle at speed. Spoilers, depending on their size, shape, and positioning, also can help reduce drag.

Wheels
Thinner and smaller wheels reduce the surface area that a vehicle needs to push through the air and reduce road friction, decreasing drag and increasing fuel mileage. In addition, fully closed, concave rims are more aerodynamic than open rims. Low rolling resistance tires also aid fuel efficiency.

Efficient Driving Behaviors

Reducing Idling
Idling for long periods of time wastes fuel and poses a health risk to people in and around the vehicle.

Removing Extraneous Items
Removing unneeded accessories from one’s vehicle can increase fuel efficiency. Roof racks, for example, can be removed when not in use. Older cars with outboard antennae can be upgraded with internal models. Removing unneeded cargo also increases fuel efficiency by reducing the vehicle’s total weight.

Smooth Driving
Periods of rapid acceleration and deceleration waste large quantities of fuel, and often do not contribute to any significant decrease in travel time. Driving at the posted speed limit, in addition to smoother acceleration and deceleration can greatly increase fuel efficiency.

Using High Gears
When driving at speed, using high gears reduces the speed of the engine and the amount of fuel it consumes.

Vehicle Maintenance
To achieve maximum fuel efficiency, motor vehicles require regular maintenance. Oil should be checked and changed on schedule and tires should be properly inflated. Fixing any serious engine tuning issues can also increase fuel economy.

Related Stories