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Why Cars Have Become Lighter

14 JAN 2014
Career Path : Automotive

Cars have become lighter largely due to consumer demand for better fuel economy. In finding ways to cut fuel consumption, automakers have reduced vehicle sizes and have been moving away from steel as a material used for vehicle frames.

Automakers have traditionally used steel in the construction of auto frames. To be sure, steel is a very strong and sturdy metal, and there is little doubt that its durability has saved many lives. Studies by the National Highway Traffic Safety Administration beginning in 1977 even found that heavier cars are safer, so people were confident about the safety of steel cars.

Traditional chassis and emerging demand for increased fuel economy

Consumers in recent years, however, have turned fuel economy into a huge selling point. This has led auto manufactures to find new ways to build cars that stretch every dollar drivers spend on fuel. A quick and easy way to make a car more fuel efficient, of course, is simply to reduce its weight. After all, smaller cars are not only more aerodynamic, they’re lighter as well.

A new look at design materials

Before long, automakers were asking themselves how to squeeze even more fuel economy out of today’s smaller vehicles. Inevitably, the focus would shift from the size of the vehicle frames to the frames themselves. Steel frames were accounting for about 60 percent of total automobile weight, and automakers were scrambling for alternatives. Before long, new cars with frames containing aluminum and carbon fiber were driven from research laboratories to dealership lots.

Critics of the newer vehicles would have been understandably concerned about the safety implications of the new frames; it was previously thought that these cars would lead to the loss of many more lives. It turns out, however, that researchers had misinterpreted the data collected during the NHTSA studies:

  • It was true that heavier vehicles were safer, but they were only safer because they were larger
  • Size was the main factor in determining automobile safety
  • The weight of a car, it was determined, was irrelevant

Long-term changes in the automobile market

These findings and auto design trends with fuel economy at their core have led to big changes in the automobile market that those interested in automotive careers would help themselves by considering. Changing the materials used in an automobile’s chassis hasn’t done very much to increase price tags, meaning that consumers now have access to vehicles that can potentially pay for themselves over time. Advancements in fuel efficiency also have certainly had a large effect on automobile weights – the weight of the average vehicle fell by 150 pounds between 2011 and 2012 alone, according to the EPA. This is due in no small part to shifts in chassis composition driven by the demand for improved fuel economy. Rather than using pure steel for vehicle frames, manufacturers now prefer aluminum alloys which integrate in the neighbourhood of 300 pounds of aluminum on average per frame. As the use of aluminum, a material with just a third of the density of steel, becomes more common, a future automotive technician shouldn’t be surprised if cars keep getting lighter.

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