New Cars Are Shedding Pounds in the Name of Efficiency and Performance

Sami Haj-Assaad
by Sami Haj-Assaad

From in-car technology to turbocharging, there is perhaps no other trend that’s fundamentally changing new cars more than the move to dramatically reduce the weight of modern vehicles.

Nearly every automaker is putting their cars on a diet in order to improve fuel economy, not to mention key driving elements. There are many ways that car companies are looking to drop weight. Some you can notice right away, and others are well hidden from the consumer. Let’s take a look at just a few of the ways automakers are reducing weight, and how it’s impacting the car.

Innovations in steel:

Hyundai is one company that’s going to great lengths to describe how it drops weight. The Korean automaker has its own steel plant, which is constantly innovating and producing new types of steel that can maintain its structural rigidity, while reducing weight.

“It’s a big part of Hyundai’s strategy” said Derek Joyce, Hyundai’s Manager of Product Public Relations. “We’re one of the few automakers who make their own steel.” Joyce talked about some of the different types of steel the Korean automaker produces, and how they differ in strength. “We apply our different types of steel to different parts of our cars to reduce overall weight,” he said.

Looking at the company’s upcoming seven-passenger 2013 Santa Fe (seen on the right) Hyundai makes sure to point out that it features the lowest curb weight against its primary rivals, besting them by as much as 461 lbs.

“Our high-strength steel allows us to have the same rigidity and safety characteristics, but without the higher weight,” said Joyce, addressing concerns about lower weight bodies resulting in flimsy frames.

Other car companies are shifting away from using just steel and exploring extensive use of aluminum for structural components. Not only is aluminum lighter, it’s also recyclable, and easier on the environment to manufacture. The down side is that it’s currently also quite expensive, meaning that for the most part, heavy use of aluminum is the domain of luxury automakers. Jaguar’s new XJ sedan uses an all-aluminium chassis that it says is 66% lighter than steel. Audi is also using this strategy in their vehicles, from the A8 flagship sedan to the R8 supercar and just about everything in between.

Weight at the core of new Mazda philosophy:

Due to the high priority of fuel economy in the consumer’s minds, Mazda has been touting its Skyactiv philosophy and technology. Mazda says that Skyactiv allows vehicles to become more fuel efficient without any compromises. A major part of Skyactiv is the use of lighter-weight platforms. The all-new 2013 Mazda CX-5 (above) crossover was built from the ground up with that in mind.

“Weight savings is the absolute essence of efficiency,” said Dave Coleman, lead project engineer at Mazda. “If we can move less mass, we use less energy, meaning an engine has to work less.”

Mazda says that every individual component in the CX-5 was examined to ensure it provides the greatest efficiency, lightest weight and appropriate levels of driver-involvement.

“Weight is the one thing we can improve, with any compromises,” said Coleman.

However, Skyactiv doesn’t just focus on the body of the car. Mazda showed us individual bolts that are lighter by at least eight grams each. That might not sound like much, but think about all the bolts in a car, and the weight savings add up.

Even the new Skyactiv engines are lighter than before. Mazda says that its new Skyactiv-G engine in the CX-5 uses redesigned components and pistons in order to reduce weight. Mazda claims “Skyactiv-G is 10 percent lighter, delivers more torque, improves fuel economy and lowers emissions.”

In upcoming vehicles, Mazda says the Skyactiv engineering philosophy aims to cut at least 100 kilograms (around 220 lbs) from each new generation of vehicle. The next vehicle that will be made from the ground up with Skyactiv in mind will be the Mazda6, which if we apply this thought, we can expect to weigh-in at around 3,000 lbs.

Even Hybrids go on diets:

Shedding weight is extra-important for hybrid or electric vehicles, which are already heavy due to the extra technology that they pack.

The Toyota Prius c (see left) gas-electric hybrid achieves its superb mpg numbers mainly by being so light weight. By using more high-strength steel the Prius c manages a total weight that’s on par with, or better than its competitors, even though it has both a gas and electric motor, and a heavy 144-volt nickel-metal hydride battery. In total, it tips the scales at just around 2,500 lbs, while achieving an average of 50 mpg.

With less weight to push around, not only were Toyota engineers able to down-size the engine to a 1.5-liter unit, but they were also able to shrink the size of the battery pack so it could fit under the rear seats.

An even better battery option for hybrids and electric cars is to use lithium-ion batteries, which are smaller, lighter and more powerful – though more expensive. Honda’s new Civic Hybrid has made the switch to lithium-ion batteries, resulting in 7 more horsepower, while being 33 percent smaller and lighter.

Frugality while staying fun to drive:

Even luxury car maker BMW is looking to reduce weight from its cars. Newer models now are equipped without a spare tire. This might sound a little risky, but BMW fits their cars with run-flat tires, which are capable of driving an extended distance while punctured. Run-Flats have had their share of critics, but BMW remains adamant that the rubber is a part of its Efficient Dynamics philosophy, which increases fuel efficiency and maintains the car’s fun to drive personality.

Additionally, BMW is working to incorporate lighter-weight materials in vehicles, going a step further than most to explore the use of Carbon Fiber Reinforced Plastic (CFRP), which is strong, but weighs lighter than steel or aluminum. CFRPs are currently used in Formula one cars, so that should be a testament to the material’s rigidity.

For several years BMW has offered carbon fiber parts on its special M performance models, including even carbon fiber roofs (seen above) on cars like the M6. Not only does this keep total weight down, but by removing weight from the higher section of the car, it improves the overall center of gravity.

Due to its cost, extensive use of carbon fiber is limited to ultra exotic machines like the Lexus LFA, McLaren MP4-12C and Lamborghini Aventador, all of which use the light weight weave for their platforms rather than steel or aluminum.

The Biggest-Loser: Car edition

Cars don’t binge on chocolate ice cream, so what happened for them to get so heavy?

“Frankly, its sloppiness,” said Coleman. “In order to make an old structure stronger, you’d just add some mass to it and if you keep piling things onto the same idea it becomes pretty inefficient.”

It’s true that chassis have to keep getting stronger in order to meet changing crash-test standards, but that’s not the only thing that adds weight.

“The bar keeps changing, from standard equipment to crash-standards,” Coleman said. But just because a vehicle is losing weight, it doesn’t mean that it has become less safe.

“We start the design of the car with the crash, and we work from there. So the safety is the fixed point,” he said. “We then work on how light we can make the car from there.”

So even though we are cutting weight, we’re not throwing away airbags, sensors and other important safety equipment.

When weight-loss means sporty dynamics:

Lighter-weight bodies allow companies to put in more frugal engines, which in turn allows for even greater fuel efficiency. With Ford’s EcoBoost turbocharged direct-injection engines we’ve seen a switch from larger displacement six or eight cylinder blocks to smaller four-cylinder units. By cutting weight, cars can also make better use of their power – for fun.

Take a look at the Scion FR-S (above), which has a weight that’s just about 100 lbs more than a sub-compact. While the car’s 2.0-liter engine generates a mere 200-hp, the car is an absolute blast to drive. Due to the trim body weight, the driver has a much more responsive vehicle, making it feel like a ‘true’ sports car. Like other vehicles, the Scion FR-S is made with a large proportion of light-weight, high-tensile steel. The car also uses electric power steering, quickly becoming the industry norm, which is lighter in weight than the conventional hydraulic power steering. Finally the FR-S uses an aluminum hood that not only saves weight, but keeps the cars center of gravity low, a crucial factor in making a sports car.

Ultimately, fuel economy and performance have many of the same goals. Like maximizing the efficiency of every drop of gasoline can also help deliver the most horsepower, putting a car on a diet doesn’t just improve fuel economy, it also helps deliver a vehicle with more fun-to-drive potential.

Sami Haj-Assaad
Sami Haj-Assaad

Sami has an unquenchable thirst for car knowledge and has been at AutoGuide for the past six years. He has a degree in journalism and media studies from the University of Guelph-Humber in Toronto and has won multiple journalism awards from the Automotive Journalist Association of Canada. Sami is also on the jury for the World Car Awards.

More by Sami Haj-Assaad

Join the conversation
  • Graeme Cowell Graeme Cowell on Jun 14, 2012

    2012 Impreza is good example of this too. Smaller 2.0 engine compared to the old 2.5. It also shed about 300 pounds from the last model. Subaru sales people claimed it made it 30% more efficient.

    • See 2 previous
    • Danwat1234 Danwat1234 on Aug 07, 2012

      Well they could make a hybrid drivetrain to the 2L engine and make it perform as well as the old 2.5L along with a bit more MPG on the hwy and a lot more MPG in the city