Drivers are eager to increase fuel economy when gas prices are high. Could it be as simple as selecting the ‘Eco’ mode found on many late-model cars and SUVs?
To find out, we recently tested ‘Eco’ mode on vehicles subjected to our tests typical fuel savings. We had a mild day with constant temperatures, ideal for these simultaneous measurements.
As we have seen in the past, the ‘Eco’ mode proved to be disappointing in both the city and road tests. road.
Available modes allow drivers to adjust power delivery characteristics, letting the car’s computer make adjustments to throttle settings that control engine performance, transmission shifting and all-wheel drive response, if the vehicle is so equipped.
The most common modes are ‘Eco’ to optimize fuel economy, ‘Normal’, and ‘Sport ‘ to increase response, primarily by holding down the gears so the engine stays at high throttle, where power is most available. You often see ‘Comfort’, for moderate driving, and ‘Snow’, for dealing with the challenges of winter weather. (Our tests are done in the default mode, generally ‘Normal’, when there are driving modes to choose from).
‘Eco’ mode tends to reduce throttle response, for faster acceleration. smoother, while shifting earlier, keeping the engine revs lower to conserve fuel.
For our fuel economy tests, we installed an online fuel gauge, rather than taking a measurement approximate filling the fuel tank. This requires one of our mechanics to cut the fuel line and connect the meter, which accurately measures fuel consumption per CC, or cubic centimeter.
In the city
At the Consumer Reports Auto Test Center we have a simulated street circuit that replicates the speeds and regular stops that drivers typically make in an urban environment. Our protocols include complete stops and accelerations at certain speeds, ensuring consistency for comparing results, and mimicking the need to move with the flow of traffic. In the end, this raised an interesting question: ‘Eco’ mode toned down the performance of the car and SUV, but we still had to move with the flow of traffic.
So, although the reduced throttle response could encourage a more moderate driving style, which would favor fuel economy, the need to reach the speed limit, within the time-limited test, meant that our testers had to accelerate the vehicle a little more to overcome just the drag added by ‘Eco’ mode.
In previous tests, we found no fuel economy advantage using ‘Eco’ mode for city driving. And it turned out to be the case again in our most recent tests.
We also tried the ‘Sport’ mode. It made both types of vehicles more agile to drive, and disabled the stop/start function, but it cost a trade-off of 2 mpg loss.
Highway
We measured highway fuel consumption during constant driving at 65 mph. This is an ideal driving scenario, with the transmission in its highest gear, known as ‘overdrive’, as it has a ratio less than 1:1. We ran this test in two directions to account for any potential impact from wind and terrain.
In this test, ‘Eco’ mode had no benefit that we could measure. And that’s not a surprise: acceleration and gear selection are not a variable when maintaining a constant speed on flat terrain.
The only way to improve fuel consumption on the highway would be to remove unused bike or cargo racks, drive in moderation, and obey the speed limit. Our previous tests have shown that both cars and SUVs pay a significant ‘toll’ in fuel consumption when going from mph to 75 mph.
Conclusion
The ‘Eco’ mode is not a magic button that allows you to save fuel instantly. Its true value lies in its ability to encourage moderate driving behavior that can make all the difference. We have seen in other tests that quiet driving can reduce consumption by 2 to 3 mpg around the city, compared to an erratic driving style.
This mode often causes a warning to appear. consumption display on the instrument panel that shows fuel economy in real time, and serves as a training method. This is perhaps the best reason to activate ‘Eco’ mode.
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Consumer Reports has no financial relationship with advertisers on this site . Consumer Reports is an independent, nonprofit organization that works with consumers to create a fair, safe, and healthy world. CR does not endorse products or services and does not accept advertising. Copyright © 2022, Consumer Reports, Inc.