When you're shopping for a new car, you have to decide on more than just style, color, and whether to get satellite radio or a CD player. Going green means looking for a car that's fuel efficient and easier on the environment than some big, heavy gas guzzler. Each gallon of gas your car uses contributes to global warming by releasing carbon dioxide—20 pounds worth for each gallon burned—and other greenhouse gases. For the average vehicle, that adds up to six to nine tons of carbon dioxide belched into the atmosphere each year. Fortunately, car technology is improving so you now have more earth-friendly choices, as explained in the next few sections.
Tip
The American Council for an Energy-Efficient Economy (ACEEE) has a database of cars rated by energy efficiency. The database, available by subscription, goes back to 2000, and you can choose models to compare. Check it out at http://greenercars.org (click the left-hand ACEEE's Green Book link).
Simply put, fuel efficiency means you get more miles on less gas, so you save money, burn less fuel, and reduce your impact on the environment—it's a win-win-win situation. Special technologies, described in the following sections, can improve efficiency, but if you're looking for a traditional car, ask these questions to get the most MPGs for your money:
What size do I need? Many people buy a bigger car than they really need. Because larger vehicles are heavier, they burn more gas. So think about how much passenger room and cargo space you'll actually use. For example, two parents, a kid, and a typical load of groceries can fit into something smaller than a minivan or SUV.
Which models get the most miles per gallon? Once you've decided on the size you want, compare the mileage ratings for different models in that size range. A good place to compare models (and get tips on fuel efficiency) is www.fueleconomy.gov.
Tip
Canadian car buyers can get mileage info from the Office of Energy Efficiency (http://oee.nrcan.gc.ca). If you're in the U.K., check www.vcacarfueldata.org.uk.
What kind of transmission should I get? In general, manual transmissions are more fuel efficient than automatic ones by about 5–10%. (Of course, you need to know how to drive a stick to get this benefit.) Go for a four- or five-speed if it's available.
Will I really use four-wheel drive? Four-wheel or all-wheel drive is great for off-roading and for maximizing control when the road is slippery. But keep in mind that this option increases fuel use by 5–10%. So it's worth assessing whether you really need four-wheel drive.
Do I need any bells and whistles? Car dealers love to pile on the options: auto climate control, power everything (windows, seats, mirrors, and so on), video systems, roof rack, sunroof, and so on. Some of these things can reduce fuel efficiency by adding weight, drawing extra power from the engine, or increasing aerodynamic drag. They also add to the cost, which means you pay more money for a less efficient car.
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Some options improve fuel efficiency, including tinted glass (you won't need the AC as much), lightweight aluminum wheels, cruise control, and tachometer or shift indicator for manual transmissions (to help you shift more efficiently). A sunroof can be a mixed blessing: If you're using it instead of turning on the AC while driving around town, it can help your mileage. But on the highway, an open sunroof reduces efficiency because it increases drag on the fast-moving car.
A typical hybrid vehicle gets its power from two sources: a gasoline-powered internal combustion engine and an electric motor. But not all hybrids work the same way. So if you're thinking about getting one, learn these terms before you go shopping:
Parallel hybrid. You might remember the terms "parallel" and "series" from high school science class. In the context of cars, they refer to the way things under the hood are connected. Parallel setups are the most common. In this kind of hybrid, a combustion engine and an electric motor are connected to the transmission. The engine and the motor can run in parallel, meaning the fuel tank supplies gas to the engine, and a set of batteries simultaneously powers an electric motor. So the engine and the electric motor can both run the transmission at the same time. Examples of parallel hybrids include the Toyota Prius and the Ford Escape.
Parallel hybrids fit into one of three categories:
Full hybrid. This type of car can run on the combustion engine, the electric motor, or a combination of the two.
Assist hybrid. The electric motor in this kind of setup doesn't have enough juice to move the car all by itself. Instead, the electric motor assists, or boosts, the gas engine.
Mild hybrid. Internal combustion engines move these cars. In general, the electric motor generates power when the car slows down. That power helps run extras like the AC, taking a load off the engine so it can be smaller than in a normal car, which makes the car lighter and increases fuel efficiency.
Serial hybrid. In this arrangement, the gas engine turns a generator that either charges the batteries or powers an electric motor that drives the transmission. That means that the gas engine never directly powers the vehicle. The Chevy Volt, currently being developed, uses serial hybrid technology.
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A plug-in hybrid (which can be parallel or serial) comes with a plug you can use to charge the car's batteries. When you drive on fully charged batteries, you're not using the gas-powered engine at all. If the batteries need recharging while you're on the road, the gasoline engine kicks in, and the car works like a regular hybrid.
Like gas engines, diesel engines use internal combustion—a series of small, controlled explosions—to convert the potential energy in fuel into energy that makes your car go. In a conventional engine, the carburetor mixes gasoline and air together, and then spark plugs ignite the mixture. But in a diesel engine, fuel gets sent into a combustion chamber, where hot, compressed air ignites it. This direct fuel injection makes diesel engines more efficient. Although diesel fuel and gasoline are both made from crude oil, diesel is heavier, thicker, and oilier. It also contains more energy than gasoline (about 18% more), and that, combined with the engine's efficiency, lets diesel engines get more miles out of each gallon of fuel.
You probably think of diesel-powered trucks as being smelly, noisy, smoke-belching monsters. That used to be the case, but today's diesels—cars and trucks—are a whole new breed. The diesel engine is 20–30% more efficient than the gas-burning internal combustion engines in most cars.
Fuel efficiency is the biggest plus of owning a diesel car. Others include performance (diesel drivers say their cars have a lot more pep) and longevity (it's not unusual for them to keep chugging along for 250,000 miles or more). And as you'll learn in the next section, you can convert a diesel engine to run on vegetable oil.
But these engines have their downsides. They're more expensive than gas-powered cars, and diesel tends to cost more and be harder to find than gas. Though they're quieter than they used to be, diesel engines still tend to make more noise than gas ones, and can be harder to start on cold mornings. But for someone like you who cares about the environment, the biggest issue is emissions. Diesel engines burn dirtier than gas ones, spewing out more smog-forming particulates and nitrogen oxides. But since they're more efficient, they burn less fuel and produce less carbon dioxide. But happily, you can make your diesel a lot more environmentally friendly by converting it to veggie fuel.
We're used to thinking that cars have to run on the liquefied remains of dinosaurs, but there are other, renewable fuel sources. Biodiesel, ethanol, and vegetable oil are all emerging as plant-based options that can reduce our dependence on oil to keep the world moving. The following sections have the details.
Biodiesel is a clean-burning fuel made from things like vegetable oil (including used cooking oil, called WVO for waste vegetable oil), algae, and animal fat. Most biodiesel is made from soybean oil and can be used in most diesel engines without any modifications. You can also mix it with petroleum-based diesel fuel, which is a good idea if you live in a cold climate because biodiesel can be sluggish when the temperature drops. Unlike straight veggie oil (covered in the next section), biodiesel is EPA approved for use as a fuel.
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Biodiesel and ethanol (the chemical name for alcohol) are both made from plant sources, but they're not the same thing. Ethanol is used as an additive in gasoline (and, increasingly, as a fuel in its own right). Biodiesel, on the other hand, works only with diesel engines and can be blended with traditional diesel fuel; it's also a fuel in its own right.
According to the EPA, biodiesel is good for the environment: It reduces greenhouse-gas emissions by 10–50% (depending on the kind of biodiesel used) compared to petroleum-based diesel. Biodiesel cars and trucks also spit out significantly less carbon monoxide, particulate gunk, and sulfates than regular diesel.
The main concern about biodiesel is how much land and resources are needed to produce fuel rather than food. If it's more profitable to grow crops for biodiesel (and other plant-based fuels) than for food, farmers will make the switch—causing food prices to rise. Higher prices for staples like cooking oil and grains would be disastrous in many parts of the world, and could lead to famine.
Planning ahead can help to solve this problem before it gets too big. For example, biodiesel can be made from things like WVO and algae instead. And because biodiesel producers use only soybean oil, the leftover soy meal can be used for food.
Another alternative fuel that's gained momentum is veggie oil, sometimes called straight vegetable oil (SVO) to distinguish it from biodiesel. You can convert diesel vehicles using a special kit, so they have two fuel tanks: one for diesel and one for vegetable oil, which is thicker than diesel. Because it's thicker, SVO needs to be warmed up (which thins it) to work properly, so diesel is typically used to start the car. Once the engine is warm, it can switch to using SVO.
Most folks who've converted their cars use WVO they get from restaurants' deep fryers. Many restaurants are happy to give away this used oil, because otherwise they have to pay to dispose of it. (How's that for a step toward zero waste?)
SVO (as well as other biofuels) is also carbon neutral: The plants it comes from (like canola, corn, and soy) take in more carbon dioxide from the air than the oil releases when it's burned, which means it doesn't contribute to global warming. And vegetable oil doesn't emit the particulates and nitrogen oxides that diesel does.
Here are some companies that sell vegetable-oil conversion kits:
Frybrid Vegetable Oil Fuel Systems (www.frybrid.com).
Golden Fuel Systems (www.goldenfuelsystems.com).
Greasecar Vegetable Fuel Systems (www.greasecar.com).
PlantDrive (www.plantdrive.com).
Veg Powered Systems (www.vegpoweredsystems.com).
Before you start fooling around under the hood, you should know that, in the U.S. anyway, there are some unresolved legal issues about using SVO as fuel. Unlike biodiesel, the EPA hasn't given it the green light as a fuel, so people who use it in their cars could face stiff fines—up to $32,000 per day—if the agency decides to enforce them. Different states also have different regulations about using WVO as a fuel: Some exempt it from fuel taxes; others expect you to pay a road tax. For these reasons, you might want to limit veggie power from SVO to things like tractors that you don't drive on public roads.