If you have a high mpg vehicle (we're talking over 30 mpg here) and you use it as your regular car, go ahead and check all the next steps off, you're done. If not, but you're considering buying one, move on to step 2. As an aside, if you absolutely need a big truck, you can substitute a biodiesel vehicle run on waste grease for a high mpg car.

Regardless of the sort of vehicle you are looking for, mileage should be one of the top criteria in choosing the vehicle. Look not only at vehicles that are out right now, but also ones coming out soon. Learn about the different technologies out there. Learn about the different types of hybrids in our Electric Cars section.

If you are looking at a high efficiency vehicle, take a look at some of the plug-in hybrid vehicles coming to market in the next couple years. These vehicles rely on electricity for the first 40 miles or so of their range and then use gasoline. They are likely worth waiting for.

There are a lot of government rebates out there for high efficiency vehicles nowadays. Take a look to see if you qualify for one.

Actually buy your high mpg vehicle. Use it for a couple weeks and see what sort of mileage you get out of it. We've set a threshold of 30mpg as "high mileage", so anything over that gets this guide checked off.