Buck’s post on his family’s decision about which car to drive highlighted a question many people are asking. He and his wife chose wisely, according to an amazing web site everyone should use: www.fueleconomy.gov. Among other things, the site allows you to compare two vehicles side by side and see how much you can expect to spend on fuel.

To use Buck’s example, he will probably get 31 mpg city and 39 highway with his 1994 Suzuki Swift, for a combined total of 34 mpg — exactly what he reported. His 1999 Isuzu Rodeo, on the other hand, will likely only get 18 mpg in city driving and 22 on the road, for an average of 20 mpg. But the comparisons don’t stop there.

It will cost Buck & Co. $3 to drive the Suzuki 25 miles because it will use .74 gallons of gas. That will add up to an annual fuel cost of $1,799, based on average miles. The Isuzu, however, will cost $5.10 to drive 25 miles and will burn 1.25 gallons of gas, for an annual cost of $3,060. Huge difference!

We’re not done yet. At the end of 12 months, the Suzuki will have used 10.1 barrels of oil while the Isuzu will burn up 17.1 barrels. Finally, the carbon footprint on the Suzuki, on a scale of 3.5 to 16.2, is only 5.4. The Isuzu? A much bigger 9.2.

If you’re trying to figure out whether trading your gas guzzler will make sense, use this site. You’ll keep from miscalculating something that could cost you mucho dinero down the line.

And Buck, one more thing. No matter which car you choose, install a K&N air filter. I did, and I’m now getting one extra trip to Jacksonville on a tank of gas. And while I’m sure you wouldn’t want a trip to J-ville, period, it’s a big help to me.