The 40 MPG Benchmark

A line has been drawn in the sand. It’s a new standard that is pushing automakers to higher levels of fuel efficiency. That threshold is 40 mpg. Not long ago, a 40 mpg car was a rarity. Reaching 40 mpg required alternative powertrains like gasoline-electric hybrid drive or clean diesel. Today, 40 mpg is being achieved with more efficient gasoline engines. Engine downsizing combined with turbocharging, advanced valvetrains, gasoline direct injection, super efficient transmissions, weight reducing materials, and aerodynamic tricks are making 40 mpg more common.

I test and review a different car nearly every week and the trend toward higher fuel economy is eye opening. Even with fuel prices near record levels, it’s a relief to know you can manage an average week’s worth of commuting, errands, and miscellaneous trips and often cover it with a twenty when it’s time to top off. That makes a huge difference in a family’s annual household budget.

The national average for gasoline was $3.53 per gallon in 2011. If you figure the difference between a car that achieves 40 mpg verses one that manages 25 mpg, you’ll find a significant difference. Using 15,000 miles per year, an average driver would spend $2,118 on gas at 25 mpg and $1,323.75 at 40 mpg. The savings totals $794.25 in your pocket at the end of the year. What could you do with an extra $15 dollars and change in your wallet each week?

Now, 40 mpg is a highway fuel economy figure and some would argue that the combined city/highway economy is what really matters. Actually, if you use the combined number the savings actually go up. A 40 mpg highway car might have a combined fuel economy of 33 mpg. A 25 mpg highway car is likely to be 20 mpg combined. Run the numbers and the annual savings is more than a grand in your pocket at the end of the year.

In my testing I find that it is pretty easy to beat EPA fuel economy estimates if you pay attention to your driving and use some basic frugal driving techniques. On many of the latest generation of fuel efficient cars I am able to easily push highway fuel economy into the mid-40 mpg range with combined averages near 40 mpg.

The EPA test cycle was revised in 2008 to provide better ‘real-world’ estimates. The new test model includes a city cycle, a highway cycle, and also factors in three additional test cycles. There is a high-speed test, another test is run with the air conditioner on, and a fifth test is preformed in cold temperatures. They are fairly extreme, too. The high-speed test, for example, hits 80 mpg at one point and acceleration is more aggressive in all the test cycles. Obviously, these three additional tests drive down the traditional city, highway, and combined numbers.

It has an effect of ‘dumbing down’ consumers’ fuel economy expectations, which can negatively impact how a driver operates a car. Lower gas mileage expectations generally lead to less efficient driving habits.

On the plus side, automakers are now cranking out some great 40 mpg cars. Fuel economy is trending upward. Some will say it’s not happening fast enough, but when you factor in the constraints of the added weight and complexities of modern safety and convenience equipment, the progress toward improved fuel economy is making real progress.


Todd Kaho is executive editor of Green Car Journal and editor of

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