The Drive for Lightweight Cars
By 2016, the US car industry will need to average 34.5 mpg and by 2025, cars will need to average 54.5 mpg. In order to meet these new requirements, manufacturers will have to implement a number of changes including new engines, technologies, and materials. Lightweight materials are one of the most important avenues to pursue because for every 10% reduction in weight, fuel efficiency is increased by 6–7%.
The Benefits of Composites
Carbon fiber composites are as strong as steel, while weighing over 75% less. The materials are the lightest to use and also the stiffest. Because of their superior mechanical characteristics, cars built using carbon fibers are some of the lightest, fastest, and most fuel efficient vehicles on the road. Composites can also absorb a large amount of energy before failure, which can make new lighter vehicles just as safe as their heavier counterparts. The only drawback is that composite materials are three times more expensive to make, meaning adoption will be slow until the price comes down. Despite the high cost, composites have been used in cars for over 30 years and are now being used for the first mass produced composite vehicles.
Composites in Use
Carbon fiber was first used in high performance vehicles such as the McLaren MP4/1, the first Formula One car to feature a carbon fiber chassis. The low weight and increased strength helped make the car one of the lightest, stiffest, and fastest to grace the track in 1981. The use of composites also allowed the engineers to design a safety cell for the driver, which would remain intact in the event of a crash, making previously fatal crashes survivable.
Over the ten years from 1981 to 1991, carbon fiber was used only on racecars because they were the only customers willing to pay the high cost for increased performance. The first carbon fiber vehicle to be sold to the public was the McLaren F1 in 1992. The million dollar sports car was built to be used on public roads but was truly at home on the track, hitting top speeds of over 200 mph and boasting a 0–60 time of just 3.2 seconds. Even with these impressive numbers, the car only weighed about 2,500 pounds (significantly less than most consumer vehicles) because of the low weight of carbon fiber.
Now carbon fiber can be found in many consumer vehicles from high-end manufacturers, but these vehicles are either low volume (such as the 400 unit Bugatti Veyron) or only use a small amount of carbon fiber.
Next year will mark a new milestone in automotive carbon fiber as BMW will begin selling the i3, the first mass produced car with a carbon fiber chassis. While previous cars used carbon fiber to save weight and go faster, the new BMW i3 will use carbon fiber to save weight and go farther. The all-electric car will tip the scales at 2,700 pounds—including the large battery needed to give it a range of 80–100 miles.
These new cars may be the first of their kind, but they won’t be the last.