Countdown to Earth Day: How weight affects a vehicle's fuel efficiency

Over the past 20 odd years, the curb weight of most vehicles sold in the U.S. has steadily increased. The latest trend, though, has automakers scrambling to trim excess pounds from vehicles. Why? Because every ounce removed from a vehicle not only improves its performance, but also boosts its fuel economy.

So, how does slashing weight hike up fuel efficiency? Let's take a look. The Environmental Protection Agency (EPA) says that for every 100 pounds removed from a vehicle, fuel economy jumps up by 1-2 percent. Of course, trimming weigh from some cars – subcompact hatchbacks come to mind – isn't that simple, but the numbers do indicate that excess weight lowers a vehicle's fuel efficiency, at least to some degree.

If we turn to a report issued by the Aluminum Association, Inc. based on research conducted by Ricardo, we find that for compact cars with 1.6-liter engines, a weight reduction of five percent led to a 2.1 percent bump in fuel economy on the EPA combined rating. Eliminating 10 percent of the vehicle's weight – a daunting engineering task indeed – boosted mileage by 4.1 percent. As you can see, vehicle weight plays a significant role in determining just how fuel efficient an automobile can be. For more on weight's affect on a vehicle's mileage ratings, check out this Greenlings article in our archives.

Note: To mark the 41st anniversary of Earth Day* this year on April 22nd, we're running a series called Countdown to Earth Day that we want to be very welcoming to new readers, both in topic and tone. We'll be returning to our Greenlings series for inspiration here, and if you have friends who you'd like to introduce to AutoblogGreen, perhaps these posts and the coming "holiday" will provide the final push to get their green car interest up.

*Ironically, the apparent traditional gift for a 41st anniversary is land. Since land - earth - is something we can't easily create, perhaps this Earth Day we can give ourselves the gift of stewardship of the land.