No matter what kind of car you drive, you'd probably love to get better gas mileage. Even if you drive an efficient hybrid vehicle, each time you fill the tank you may find yourself thinking, "Wouldn't it be great if I could get even more mileage? Like, more than 100 miles per gallon (42.5 kilometers per liter)?" Well, if a group of visionary engineers have their way, you just might.
People like energy policy expert Amory Lovins, designers at a company called Fiberforge and even automotive engineers at Volkswagen have been hard at work trying to create cars that are incredibly light and ultra efficient. The result: hypercars. With advanced materials and alternative fuel systems, hypercars don't have to sacrifice safety, performance or luxury in the name of fuel efficiency.
If you think automotive technology is ready to evolve after staying basically the same for the last 50 years, then this article will explain why you might be right. Instead of steel-framed multi-ton vehicles powered by internal combustion engines, we're going to show you cars made of carbon-composite materials that are lighter and stronger than steel, with sleek aerodynamic shapes and incredibly efficient engines. In fact, some of these cars are so efficient that you could plug them in and return power to the grid for a discount on your electric bill. This isn't just pie in the sky futurism, either. We'll show you some hypercars that are on the road today.
If you're planning to design a super-efficient car, the first thing you need to do is figure out what makes the vehicles currently on the road so inefficient -- it turns out to be a pretty long list. Find out what tops the list on the next page.
Few experts would argue with the idea that the biggest problem with modern cars is weight. According to the Environmental Protection Agency (EPA), each 100 lbs. (45.36 kg) removed from a car can increase fuel mileage by 1 to 2 percent. The exact number depends on the size of the vehicle and its engine -- the smaller the car, the more dramatic the increase in fuel mileage. Now, 1 to 2 percent might not sound like a lot, but it adds up. If you could remove 2,000 lbs. (907.2 kg) from a car, you might increase your mileage by up to 40 percent. But the benefits don't stop there. If a car is designed from the ground up to be approximately one ton lighter, it won't need a big engine to get the same performance. The heaviest part of the any car is usually the engine block, so if you can use a smaller engine, you're saving even more weight. On top of all that, you won't need to carry around as much fuel, since that smaller engine will burn less. A gallon of gas weighs about 6 lbs. (2.72 kg). If you have a 20 gallon (75.69 liters) fuel tank in your SUV, you burn a lot of fuel accomplishing nothing but carrying around fuel. Once you make a car significantly lighter, you can reduce the weight of many components, including the brakes, suspension and even the tires [source: USA TODAY].
The inefficiency doesn't end with weight, though. Many modern cars have air-conditioning systems that are far more powerful than they need to be for the small enclosed space they are designed to cool. In addition to extra weight, they draw a significant amount of power from the engine.
Tires are another energy sore-spot. Most tires aren't designed to minimize rolling resistance, which means the engine has to push even harder to move the car. Sidewall flex in the tires wastes even more energy. And every time you hit the brakes, a large amount of energy is dissipated as heat. You guessed it -- more energy loss.
Finally, while many vehicles do have aerodynamic body shapes, not every car has an optimal aerodynamic profile. If wind resistance doesn't seem like a big deal, think about how much force pushes back on your hand when you stick it out the window of a moving car. Now imagine that force pressing against the entire front surface of the car.
What's the net effect of all this inefficiency? Let's use a basic example -- how about your typical drive to work? All you need to accomplish is moving yourself from one point to another, along with maybe a briefcase or lunchbox. Yet, on the drive there, you're also hauling about two tons of steel along with you. According to Amory Lovins, 90 percent of the energy generated by the engine in your vehicle never even makes it to the wheels, because most of it is lost as heat as the engine and drivetrain parts rub together. Ultimately, only 0.3 percent of all the power your engine puts out is actually used to move your body [source: AutoblogGreen].
Now that you know which parts of our cars are wasting energy, you can go about designing cars that do better. Find out how on the next page.
Ultra Light and Hyper Efficient
Remembering what you've learned from the previous page, if you were to design a car to be the most fuel-efficient vehicle possible, yet still practical for everyday driving, where would you start?
The chassis might be a good place to begin. The steel frame of a standard car is quite heavy. It's also very strong, so if you want to make it lighter, you'll need to find something that can withstand the stresses of carrying heavy loads and retain the ability to absorb impacts to protect the occupants. Some automakers have already experimented with higher-quality steel, which is stronger than regular steel, allowing less of it to be used [source: USA TODAY]. But if we really want to slash the pounds, we need to look at carbon fiber. When it's properly prepared, carbon fiber is 10 times as strong as steel and weighs much less. Replacing all the steel in a car with carbon fiber can reduce the weight by up to 40 percent [source: Green Car Congress].
The vehicle's body is another area where considerable improvements can be made. The shape of the car should be tested in a wind tunnel to make sure it has the optimum aerodynamic shape. Anything that sticks out from the surface of the vehicle should be streamlined, such as side mirrors, door handles and even vehicle badging. The body should be made out of strong, yet lightweight, carbon fiber as well.
When it comes to the vehicle's power plant -- the engine -- you'll have to make some choices. There are several ways to power the car that are better than internal combustion engines, but the one you choose will largely depend on the technology that matures fastest. Hydrogen fuel cells only emit water, and they could be efficient if a clean and green method of producing hydrogen is found. Electric motors that run on batteries and plug into wall outlets are technically the most cost-effective once you do the math of converting watt-hours per mile (watt-hours per kilometer) to miles per gallon (kilometers per liter) [source: Hypercars]. That's especially true if you charge at off-peak times and have access to clean electricity, such as wind or hydro power. Sometimes you might want a little extra range or more power than an electric motor can provide, so it might be a good idea to use a very efficient combustion engine. An aluminum block will keep the weight low, and you could probably even get by with three cylinders considering how light the car is.
The interior is one area of the vehicle often overlooked in weight reduction. There are a lot of opportunities for weight loss here. For example, you can avoid heavy seat frames by making the seats out of carbon fiber and even integrating them into the chassis. A few padded areas will make them snug and comfortable, even without excess padding, foam and upholstery. You can cut back on the carpeting, too. A small compressor will run the modest air conditioning unit, but it will keep the car very cool because the roof is insulated and the windows are double-paned. There's no sunroof -- not only would it let in too much summer heat, but sunroofs actually add weight to a vehicle, and reduce chassis stiffness. We'll want to listen to music while we drive, but we don't need a huge amplifier or thunderous speakers. A modest sound system will save weight and still sound great.
Of course, you'll also want to remember to use low-rolling-resistance tires which allow the car move along easily without sacrificing traction. The sidewalls of these tires are designed to be very stiff, so they won't flex and waste energy -- a feature that improves handling, too. The tires should also use run flat technology so you won't need to carry the extra weight of a spare tire or even a heavy vehicle jack.
There you have it -- you've just designed our own hypercar. Next, let's take a look at hypercars that already exist.
Hypercars on the Road
Several companies have produced hypercars, though most of them are concepts or test vehicles. There really is no strict definition of hypercar -- it simply means a car designed to be very efficient, generally several orders of magnitude better than your average showroom car. The best hybrids available in 2008 can achieve mpg ratings in the 40s (km/h ratings in the 70s) under optimal conditions, which is excellent, but not quite hypercar material.
Interestingly, some companies have been practicing hypercar theory for decades, although they haven't taken it to the extremes necessary to achieve 100 mpg (160.93 km/l) or more. Lotus is a British company known for its lightweight, agile high-performance cars like the Elise. Their design philosophy involves stripping away anything unnecessary to keep weight minimal. This gives the Elise excellent handling and amazing acceleration, even with a four-cylinder engine. Smart Cars incorporate hypercar principles as well, with a small, light design intended to carry people in urban areas.
The Rocky Mountain Institute developed a hypercar they call the Hypercar Revolution. Its design is similar to the hypothetical hypercar we designed on the previous page. The RMI Hypercar is a small SUV/crossover that seats five adults and can tow a half ton up a steep slope, but it's an ultralite vehicle.
Volkswagen built and tested a hypercar called the L1 in 2002. It's a radical design that's shaped like the cockpit of a fighter jet. There's room for the driver and one passenger seated directly behind the driver, plus a little cargo. The hatch swings open sideways, and the interior, while tight, appears to be comfortable. The L1 is powered by a one-cylinder diesel engine and can drive for 100 kilometers (62.14 miles) on a single liter (0.26 gallons) of fuel -- hence the name [source: Wheelspin].
General Motors and Scaled Composites created the Ultralite, a technology demonstration car made of carbon fiber and plastic. It proved that such designs were possible by a U.S. automaker, but GM has not put any hypercars into production [source: Scaled Composites]. Daihatsu and Honda also have hypercar development programs that have resulted in several concept designs, but nothing has showed up at the local dealership yet.
Nevertheless, energy costs worldwide are putting pressure on automakers to offer increasingly efficient vehicles. If carbon fiber construction comes down in price, we could be seeing ultralight hypercars on the road within the next few years.
For more information about hypercars, lightweight automotive technologies and other related topics, follow the links on the next page.
Related HowStuffWorks Articles
More Great Links
- Ball, Jeffrey. "Tilting at Energy Windmills: Amory Lovins believes the U.S. can drastically slash its oil consumption. Here's how." The Wall Street Journal. July 25, 2005. (July 26, 2008) http://www.rmi.org/images/PDFs/Energy/E05-07_TiltingAtEnergy.pdf
- Environmental Protection Agency. "Gas Mileage Tips." (July 26, 2008) http://www.fueleconomy.gov/feg/driveHabits.shtml
- Green Car Congress. "Toray, Nissan, Honda Partner on Carbon Fiber for Cars." July 26, 2008. (July 26, 2008) http://www.greencarcongress.com/2008/07/toray-nissan-ho.html
- Hypercars.com. "Hypercars: Ultra-Modern, Super-Efficient, High-Performance Cars." (July 26, 2008) http://www.hypercars.com/
- Linton, Lascelles. "Eco-tech Future Fuels." AutoblogGreen. August 20, 2007. (July 26, 2008) http://www.autobloggreen.com/2007/08/20/liveblogging-eco-tech-future-fuels/
- Scaled Composites. "GM Ultralite Show Car." (July 26, 2008) http://www.scaled.com/projects/gmcar.html
- Wheelspin. "Ferdinand Piëch Drives 1-Litre Car to Volkswagen's AGM." April 15, 2002. (July 26, 2008) http://www.ltv-vwc.org.uk/wheelspin//ws_may_2002/vw_bubble_car.htm
- Woodyard, Chris. "Auto components lighten up to improve mileage." USA TODAY. October 7, 2007. (July 26, 2008) http://www.usatoday.com/money/autos/2007-10-07-lighter-weight_N.htm