Emissions, miles per gallon, recyclable - all are words or terms used often on the eco-friendly side of the automotive industry. Maybe you've decided your next vehicle will definitely be an earth-conscious one, or maybe you're still toying with the merits of buying green. Regardless of your position, there are still specific characteristics to look for in any vehicle purchase you make if you have the goal of reducing the environmental impact of your wheels.

Miles per gallon
Miles per gallon, or mpg, is exactly as the name indicates and refers to the fuel economy of a vehicle - as in the amount of fuel required to travel a specific distance. The more fuel efficient vehicles go a further distance per unit of fuel. In other words, size does matter here because the bigger the number, the better in this case. For example, the Toyota Highlander has a rating of 21 mpg for city driving and 31 mpg for highway driving, while the Toyota Highlander Hybrid is rated 33 mpg in the city and 34 mpg. Which if broken down further, means the hybrid will travel 12 and 13 miles further during city and highway travel respectively than the conventional Highlander.

Emissions
The emissions your vehicle releases into the air depends are dependent on several factors including the type of vehicle you use, the distance you travel, the way you drive and where you go. For every liter of gasoline your vehicle uses, 2.4 kilograms of carbon dioxide are produced. The vehicle you drive is also important to consider; for example, if you drive 20,000 km per year, a standard SUV is responsible for six tonnes of emissions, a mid-sized sedan will produce four tonnes and a gasoline-electric hybrid vehicle is responsible for two tonnes.

If you know you'll be driving a substantial distance throughout the year, choosing a vehicle that outputs few emissions is essential to reducing the environmental impact of your driving habits.

Recycled/recyclable materials
Check to see if any components of the vehicle you are interested in are made from recycled parts or material. For example, the 2008 Ford Escape features cloth seats made from recycled material, while Mazda and Toyota both re-used old bumpers to make new ones. Ten per cent of the plastic in Mini Cooper car comes from recycled material. The radiator side baffles belonging to Cadillac's SRX are made from 50 per cent recycled rubber, an initiative that ended up saving 2,000 old tires from landfills during the 2004 production year.

In even better news, it turns out that often times over three-quarters of a vehicle's materials are recyclable, including plastic, rubber and vinyl. Nearly 100 per cent of the metal from old cars is recycled and used in the production of new vehicles. And according to Ward's Motor Vehicle Facts and Figures, 84 per cent of a vehicle's content is recycled these days.

Engine size
Generally the bigger a vehicle's engine, the more fuel it will burn to generate torque and horsepower. This tends to be the case with engines six cylinders or larger. Generally the fewer cylinders a vehicle with a smaller engine has, the more fuel-efficient it will be.

If you still can't give up your gas-guzzler habit and aren't about to start driving a hybrid vehicle, look for a vehicle that offers variable displacement technology such as Honda's Variable Cylinder Management, which deactivate the cylinders of a vehicle when not in use to improve the unit's fuel economy. This way your vehicle won't burn fuel it doesn't require under normal driving conditions.

Electric/Hybrid/ Vehicles
A hybrid vehicle uses two sources of power, typically gasoline and electricity these days, to power a vehicle. Think of it as a compromise. You'll gain fuel efficiency and reduce the pollution generated by a gasoline-only vehicle without losing the convenience of traveling longer distances when need be, which can be the case if an electric car needs recharging.

Manufacturing process
The green features of a vehicle itself are not the only factors to consider. If you're trying to truly make an earth-conscious choice, look into the manufacturing process behind the vehicles you may purchase. While a big truck or SUV may not be fuel-efficient, it's possible it was still made in an eco-friendly way. A Ford plant in River Rouge, Michigan for instance, uses technology to conserve energy at the facility, gets hot water and energy from solar panels and features a green roof (literally), over 10 acres of rain-filtering plants that also turns harmful carbon emissions into oxygen.

On the other hand, a choice like the Toyota Prius Hybrid may be less harmful to the environment when on the road, but as it's being built, uses a battery containing nickel that is made while releasing toxic sulfur dioxide fumes into the atmosphere and killing the plant's surrounding vegetation.

In other words, appearances can be deceiving. This could be true of any vehicle you are contemplating so be sure to do your research in advance so you can make the choice that's best for you - and the earth.

» Edmunds.com