Great ideas have a way of coming back. And so it is with the engineering mantra of Lotus founder Colin Chapman: While Cadillac was bulking up the Coupe de Ville with extra chrome in the 1950s, Chapman was obsessed with making the lightest cars in the world.
Working out of a stable in a London back alley, Chapman pursued his vision: He removed rivets to shave weight, carved down suspension arms to make them lighter and made engines do double duty, acting as both power sources and structural supports.
Chapman had seen the future. Today, every car maker in the world is focused on mass reduction – it has become the Holy Grail of automotive design. With rising fuel prices and ever-tougher emission standards, car manufacturers have no choice but to make their machines more efficient, and weight-reduction is a key strategy.
"It's a major priority," says Ruben Archilla, manager of research and development at Mazda USA. "Every gram counts."
Every car in Mazda's lineup has been re-engineered to reduce weight while maintaining safety. The 2015 MX-5 roadster, for example, lost 100 kilograms compared to its predecessor – a reduction that will improve handling and braking while reducing fuel consumption by about five per cent.
"Mass reduction is the name of the game," says Chris Goczan, national product manager for Mercedes Canada. "It benefits every aspect of performance. The horsepower wars are over – now it's about the complete package."
The drive to reduce weight is reshaping the industry. Jaguar's upcoming XE saloon is more than 75 per cent aluminum. Mercedes made its new C-Class sedan larger and lighter by using advanced steel alloys combined with aluminum suspension components. Ford rocked the truck world by announcing that the F-150 pickup, will have a body made of aluminum instead of steel.
The F-150 provides a case study on the cascading benefits of mass reduction. Since they have less mass to deal with, engines, brakes and suspension can also be lighter. Altogether, the new F-150 is expected to weigh about 700 pounds less than its predecessor – a reduction of 15 to 20 per cent.
When price is no object, the material of choice for weight-conscious designers is carbon fibre. Exotics like the McLaren P1 and Porsche 918 use it extensively, and many of their components are formed in high-temperature autoclaves that bond the carbon under intense pressure. The result is super light, super strong parts, but the composite materials also determine the high price of the cars.
Today's engineers face challenges that their predecessors never imagined. Governments have legislated strict fuel economy and safety standards, and consumers expect higher levels of luxury and performance. They also demand value.
"We have to have more content and crash structure, and still keep weight down," says Archilla. "The laws of physics haven't changed, so it isn't easy."
Harlan Charles, who manages the Corvette program at Chevrolet, echoes Archilla. "It's a balancing act," he says. "We talk about mass reduction every single day."
The new C7 Corvette is an example of the complexities that engineers face as they fight to reconcile the conflicting demands of the car market.
As it designed the C7, the Chevrolet team shaved 45 kilograms from the frame and 17 more from the body panels. It lightened the rear hatch, and used hollow suspension control arms. At completion, the C7 was 68 kilograms lighter than its predecessor.
Then came the add-ons. New structural safety requirements added almost nine kilograms. Interior appointments and safety features added 7.7 more. Installing an extra ratio in the transmission bumped its weight up by five kilograms. Upgraded seats cost another 7.8 (the seats in the previous Corvette had been widely criticized, and better seating was considered a market requirement). Then came anew infotainment system that includes Bluetooth, a video camera system and an on board lap timer, for a further gain of 14.2 kilograms.
By the time the engineering team was finished, the C7 Corvette weighed 1,475 kilograms – 25 less than a 1981 Corvette. This was a monumental achievement: the 1981 car didn't have impact protection beams, airbags, anti-lock brakes or GPS navigation. Its transmission was a four-speed, and it made 195 horsepower. The 2014 has advanced safety systems, an eight-speed transmission and 460 horsepower.
"A lot of work went into putting everything into the car and keeping it light," says Charles. "But the end result speaks for itself. You get a supercar that does 29 mpg (8.1 litres/100 km) on the highway."
The quest for mass reduction calls for both advanced materials and fastidious attention to engineering detail. Mazda designers reduced the number of bolts on the MX-5's wheels from five to four, redesigned the hubs and spindles the wheels attach to, and spent thousands of hours optimizing the shape of its monocoque body structure to minimize material use.
Chief Corvette engineer Tadge Juechter oversaw the development of a hydro-formed aluminum chassis and lightweight body panels. For the upcoming Z06 model, his team created an ultra-light drive shaft made of carbon fibre.
Almost every manufacturer has switched to electronic power steering, which weighs less than traditional hydraulic systems, and consumes less power. Even the most mundane systems have been put on a diet – the metal levers and pushrods that once controlled ventilation systems are gone, replaced by lightweight electronics.
Some of the savings have been eaten away by consumer demand for comfort and luxury – like the Corvette's beautiful seats. No manufacturer would dare offer a car with the Spartan accommodations that Chapman insisted on during his heyday at Lotus. After Chapman died of cancer in 1982, the company did make modest improvements to creature comfort.
What comes next? More comfort, but more weight reduction, too. "There's a lot that you have to put in," says Charles. "But you can never stop thinking light. That's how it is now."
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