Industry Market Trends
Automobile Manufacturers Pursue a Variety of Strategies to Improve Fuel Economy
February 25, 2013
the White House said in an announcement, "this move will nearly double the fuel efficiency of those vehicles compared to new vehicles currently on our roads." The Administration says the new standards "will save consumers more than $1.7 trillion at the gas pump and reduce U.S. oil consumption by 12 billion barrels." What measures will be used to comply with these aggressive new standards for vehicle efficiency? The White House's announcement doesn't go into much detail but does make mention of "advanced gasoline engines and transmissions, vehicle weight reduction, lower tire rolling resistance, improvements in aerodynamics, diesel engines, more efficient accessories, and improvements in air conditioning systems." These technology targets fit into the U.S. Department of Energy's (DOE) explanation of "where the energy goes" when a car moves down the road. Consumption of energy varies depending on whether you're talking about city or highway driving, but DOE says that combined city and highway driving place the following energy requirements on the fuel usage for an automobile:The auto industry has plenty of incentive to improve vehicle efficiency. In August of 2012, the Obama Administration finalized new fuel efficiency standards that will increase fuel economy for cars and light trucks to an unprecedented 54.5 miles per gallon (MPG) by Model Year 2025. "When combined with previous standards set by this Administration,"
- 70-72 percent -- Engine losses, mostly thermal losses from things like the radiator and exhaust heat
- 17-21 percent -- Power to the wheels, dissipated through wind resistance, rolling resistance and braking
- 5-6 percent -- Parasitic losses through things like the water pump and alternator
- 5-6 percent -- Drivetrain losses
- Cylinder deactivation is an effective technology, especially for six- and eight-cylinder overhead valve engines. Cylinder deactivation essentially shuts off some of an engine's cylinders during light-load operation, reducing fuel consumption by four to 10 percent at an incremental retail price equivalent (RPE) of $550.
- Stoichiometric direct injection involves controlling precisely the amount of gasoline used in the cylinders in a fuel-injection engine, optimizing the amount of gasoline used. This technology offers a 1.5 to 3 percent fuel reduction at an incremental RPE of $230 to $480.
- A combination of downsizing and turbocharging produces a smaller, more efficient engine without sacrificing power. This approach can reduce fuel consumption by 2 to 6 percent. The incremental RPE can vary widely, says NAS, from almost nothing to $1,000.
It's true that a lot of energy -- 70 percent or more -- is lost due to the inefficiency of the engine. But the best way to avoid these losses is to reduce the amount of energy that must be produced by such an inefficient device in first place -- for example, by making the vehicle lighter. More than two-thirds of the energy required to move a vehicle is due to its weight, as opposed to drag and rolling resistance. If you cut the weight in half, then you need only half as much mechanical energy to power the vehicle. You basically can halve the engine as well.RMI is focusing much of its investigative work right now on carbon fiber, because of its physical properties. Do Electric Vehicles Represent the Most Promising Long-Term Solution? In the big picture, electrification represents one of the more important strategies for improving vehicle efficiency. At the lecture I attended last year, RMI's Lovins said he thinks vehicle light-weighting and electrification should go hand-in-hand:
The engine gets smaller, and that makes electric batteries more affordable, and the costs fall. They can also be charged easier. Three interlocking technologies will make it possible: advanced materials, electric propulsion, and manufacturing... This shift in autos is as game-changing as moving from the typewriter to the computer. Lighter cars makes affordable the electrification of the auto industry.RMI's Agenbroad tells me that "Electricity is about the same price as gasoline in energy equivalent, but the electric power train is two or three times more efficient than the internal combustion engine." DOE says that electric vehicles (EVs) "convert about 59 to 62 percent of the electrical energy from the grid to power at the wheels," compared to conventional gasoline vehicles, which "only convert about 17 to 21 percent of the energy stored in gasoline to power at the wheels." EVs offer the added environmental benefits of quieter operation and no tailpipe emissions.