Back when Americans paid a few cents a gallon for gasoline, nobody worried much about fuel efficiency. All that changed with the Arab Oil Embargo of 1973.
The Organization of Petroleum Exporting Countries (OPEC) cartel reduced the flow of crude to a trickle, driving up costs. This led to mile-long lines at the pump and gas rationing unseen since World War II. Congress reacted in 1975, with the Corporate Average Fuel Economy (CAFE) standard. They've been tinkering with it ever since.
Historically, the CAFE standard has been the sales-weighted harmonic mean fuel economy, expressed in miles per U.S. gallon (mpg of a manufacturer's fleet of current model year passenger cars or light trucks with a gross vehicle weight of 8,500 pounds or less, manufactured for sale in the United States).
The harmonic mean is used because it is appropriate for situations when the average of rates is desired, and it tends strongly toward the lowest numbers on the list. Compared to the arithmetic mean, it may mitigate the influence of large outliers and increase the influence of small values.
The original intent of the CAFE standard was to improve the average fuel economy for cars and trucks sold in the United States.
It works this way: if the average fuel economy of a manufacturer's annual fleet of vehicle production falls below the defined standard (currently 30.2 mpg for passenger cars and 24.1 mpg for light trucks), a built-in penalty is assessed. The penalty requires the manufacturer to pay $5.50 for every 0.1 mpg below the standard, multiplied by the manufacturer's total production for the U.S. domestic market. Several manufacturers are paying it.
In addition, a Gas Guzzler Tax is levied on individual passenger car models (but not on trucks, vans, minivans or SUVs) that get less than 22.5 miles per gallon.
That's all about to change. With the latest and most stringent iteration of CAFE adjustments looming, automakers are in a panic trying to meet new standards that dictate that the combined U.S. light vehicle fleet must achieve 35.5 mpg by 2016. Design engineers are being pushed to the limits to design lighter, more fuel-efficient vehicles in sizes Americans are accustomed to driving.
Preparing for the 2016 standard, or at least coming close to it, has caused automakers to look at vehicle construction materials in a new way. While recently aluminum and alloys have been the primary way manufacturers have chosen to lighten the structure of vehicles, meeting the new standard calls for a fundamental change in the vehicle structure (called the body in white by automakers).
While high-end automakers like Jaguar and BMW have used aluminum and expensive alloys to lighten the body in white, the cost of retrofitting assembly lines and the engineering effort involved are extremely expensive. What automakers need is a material that acts like mild steel in vehicle construction and repair but is significantly lighter.
A recent investment by General Motors Ventures (the investment arm of GM) may shed some light on the direction that one of the world's largest automakers intends to take. Recently, GM Ventures announced a "significant" investment in NanoSteel Corporation. Rhode Island-based NanoSteel has developed a new class of advanced high-strength steel sheet with an exceptional combination of high strength and high ductility that allows for cold-formable steel. Ductility is a term used to describe a material's ability to take a shape via the standard stamping process without losing strength or fracturing.
NanoSteel is about 20 percent lighter than regular cold-rolled automotive-grade steel, but acts like it for stamping and, presumably, for collision repairs. This represents a major advantage over Boron-infused steel and other alloys; it doesn't require heat to form nor does it require that the assembly line change to use it in place of cold-rolled steel.
While we've seen a lot of aluminum use in high-end vehicle structures, NanoSteel may be the ticket for large-volume automakers to use a lighter material in their body in white structure without having to use aluminum or heat-formed alloy. This should be seen as good news for shops: a potentially easier-to-work-with light material that won't require costly upgrades to repair. And it's about time shops got some good news regarding the future of vehicle construction!
Greg Horn is vice president of industry relations for Mitchell International.
