How green can vehicles go now? There’s no perfect solution, but it might be down the road.
Click on the images below to check out vehicles already on the road, and some that might be rolling along in the not-too-distant future.
Smaller vehicles mean better fuel efficiency. Super-compact cars such as the Mini Cooper and the two-seater Smart ForTwo are some of the smallest of the small. The Smart delivers 36 miles per gallon (m.p.g.), and the Mini Cooper manual transmission gets about 32 m.p.g. A new Smart “micro hybrid” design due out in 2009 is promising more than 60 m.p.g.
How green are they? They get great gas mileage, but they’re still burning gas.
Challenge: Convincing drivers that these tiny vehicles can really get the job done.
ADVANCED GASOLINE VEHICLES
More efficient engines, aerodynamic design, better transmissions and tires, as well as strong, lightweight materials, are all ways to make any car burn less gas. All this technology is on the road today, but it hasn’t all been put in one car yet. New government standards requiring cars and trucks to average 35 m.p.g. by 2020 should increase fuel-efficient options across the board.
How green are they? These types of vehicles would still burn gas, but a lot less than most cars.
Challenge: More technology per car could mean higher prices up front.
Diesel fuel packs more energy than normal gas and puts out less pollution that contributes to global warming. The best diesels are sold in Europe. Cleaner options should be available in the United States soon.
How green are they? Although more efficient and cleaner in some ways than gas, diesel still cranks out a lot of soot (also known as “particulate matter” or “PM”), a very unhealthy substance.
Challenge: Technologies to clean up PM are expensive.
Some biodiesel is made from animal fat and grease. You can actually take old fryer grease from fast food joints and use it as fuel. Other biodiesel comes from plants on farms, just like ethanol. A diesel vehicle can be converted to run on biodiesel, which some cities are doing with their public transportation.
How green are they? It can beat gas but, like ethanol, it depends on how the biodiesel is made.
Challenge: Finding the fuel can be hard, it can run into problems at cold temps, you’ll void the warranty on your car if you use it — and your car might smell like French fries.
Ethanol is a fuel that can come from plants such as corn, soy and grass. Almost any car can use up to 10 percent ethanol, but flex-fuel vehicles (FFVs) are made to use up to 85 percent, along with gas.
How green are they? That depends on how the ethanol is made. Some is a lot better than gas; some is worse (between a 30 percent decrease in global-warming pollution to a 20 percent increase). Also, the most fuel-efficient FFV, the Chrysler Sebring, gets only 22 m.p.g. running on gas and only 16 m.p.g. on ethanol.
Challenge: Creating a car that is fuel-efficient enough to take real advantage of what ethanol might have to offer. Plus, fueling stations are hard to find in many parts of the country.
Hybrid vehicles have gas engines paired with electric motors and large batteries. When you hit the brakes, the car uses that energy to charge the battery. The most efficient hybrids use their electric batteries to boost m.p.g. rather than speed or acceleration.
How green are they? The Toyota Prius is the most fuel-efficient four-door on the road, getting 46 m.p.g., with the Honda Civic Hybrid coming in second at 42 m.p.g.
Challenge: Still burning gas.
PLUG-IN HYBRIDS AND ELECTRIC CARS
Plug-in hybrids are equipped with a gas engine but are made to use it only rarely, and electric cars have no gas tank at all. You plug the vehicle into the wall to recharge, just like reusable batteries.
How green are they? Cleaner than gas, but how much cleaner depends on where the electricity comes from. A coal-burning power plant? Not so good. Solar panels on your roof? Awesome.
Challenge: The driving range of the batteries before needing to be recharged, plus plug-in hybrid batteries are especially pricey.
HYDROGEN FUEL-CELL VEHICLES
Fuel-cell cars use hydrogen tanks and oxygen in the air to produce power. The only thing that comes out of the tailpipe is water.
How green are they? Very. Fuel-cell technology leads to even less overall waste than batteries.
Challenge: It may be a long time before most drivers can get their hands on a hydrogen fuel-cell car, since figuring out how to make the fuel-cell engine and hydrogen production clean and affordable is still years away.