aaa-logo-92x58
service truck Roadside Assistance | location Find a Store

AAA: “Miles-to-Empty” Warning Fuels When Drivers Decide to Fill Up

New Research Finds Drivers Should Not Rely Too Heavily On In-Dash Fuel Economy Displays

BELLEVUE, Wash. (Jul. 27, 2021) — Drivers who rely too much on in-dash fuel economy displays that estimate the number of miles a vehicle gets per gallon — including how many “miles to empty” — could be taking unnecessary risks with their rides. AAA tested the accuracy of these systems and found these estimates vary significantly over shorter trips or are dependent on the consistency of things that affect gas mileage like speed and acceleration. A previous AAA consumer survey found 74% of drivers had used that “miles to empty” display to determine when they fill up. To avoid running out of gas, AAA recommends drivers fuel up when their gas gauge reaches a quarter of a tank.

“People want to get the most out of a tank of gas, especially when prices are higher,” said Megan McKernan, manager of the Automotive Research Center. “Collectively, the systems we tested were relatively accurate, but a closer examination of different driving scenarios revealed significant variability based on changes in speed, acceleration and distance.”

Testing Shows Driving Habits Directly Impact Fuel Economy

AAA in collaboration with the Automotive Research Center (ARC) of the Automobile Club of Southern California, used a dynamometer, essentially a treadmill for vehicle testing, to run selected vehicles through a series of simulated driving scenarios to determine the accuracy of the fuel economy estimation and range value (aka “miles-to-empty”) systems.

On average, the fuel economy display of the vehicles tested showed a relatively low error of 2.3% as compared to the fuel economy measured by the dynamometer. However, individual vehicle error varied greatly, ranging from −6.4% to 2.8%. The negative number indicates that one test vehicle overestimated fuel economy by 6.4% or 2.2 mpg, while another underestimated it by 2.8% or 0.9 mpg. These specific results suggest that each vehicle reacted differently to changes in driving and its accuracy can be impacted by driving style and conditions.

Testing of the “miles-to-empty” display found similar result fluctuations across driving scenarios. While each manufacturer likely uses a unique algorithm to estimate vehicle range, it can be assumed that some historical driving data is also used to determine the vehicle’s fuel efficiency for future driving. Therefore, the range estimation, at any given point, is affected by the vehicle’s most recent driving conditions.

“We ran our test vehicles through different driving situations ranging from cruising at highway speeds to being stuck in traffic to typical city driving,” said McKernan. “Despite the irregularities our testing found, a vehicle’s fuel economy display is an important tool to understand how different driving styles impact how efficiently a vehicle uses fuel.”

The information displayed by these systems can give drivers a clearer picture of how their specific driving habits influence their fuel economy. To do this, drivers should reset their vehicle’s trip data after filling up, and then watch how their fuel economy display changes as driving conditions change.

Maximizing Fuel Economy is Key as Gas Prices Reach 7-year High

In recent weeks, gas prices have reached their highest point in seven years. To offset some of this additional cost, AAA recommends drivers do the following:

Plan ahead and run multiple errands in one trip and, whenever possible, avoid times of day when traffic is heavier.

If you own more than one car, use the most fuel-efficient model whenever possible.

Avoid hard acceleration to maximize fuel economy, and always inflate your tires to the recommended pressure found inside the driver’s side door or owner’s manual.

Remove unnecessary and bulky items from your car. Minimize your use of roof racks and remove special carriers when not in use. Smaller cars weighed down by heavy cargo will have a greater reduction in fuel economy than larger models designed to carry more weight.

Consider minimizing your use of air conditioning. Even at highway speeds, open windows have less effect on fuel economy than the engine power required to operate the air conditioning compressor.

In hot weather, park in the shade or use a windshield sunscreen to lessen heat buildup inside the car. This reduces the need for air conditioning (and thus fuel) to cool down the car.

While these tips will help improve fuel economy, AAA reminds drivers it’s best to always have at least a quarter of a tank of gas. This will ensure drivers have enough fuel in case of unexpected delays but also helps to prevent fuel pump damage that can occur when a vehicle’s gas tank is regularly run down to empty.

About AAA Washington:

AAA Washington was established in 1904 by 10 prominent Seattleites determined to champion the betterment of motoring conditions and laws; the preservation of Washington state’s natural beauty; and the promotion of Washington as an unrivaled tourist destination. More than a century later, the club continues to pursue these on behalf of its 1.2 million members. 

AAA Washington provides a variety of exclusive benefits, including roadside assistance, discounts, maps, and personalized trip planning, to members. AAA was recently named one of the most trusted travel and automotive brands in the U.S. Additional information is available through the company’s stores in Washington and northern Idaho, at www.AAA.com, or by calling 1-800-562-2582. 

About AAA Foundation for Traffic Safety:

Established in 1947 by AAA, the AAA Foundation for Traffic Safety is a nonprofit, publicly funded, 501(c)(3) charitable research and educational organization. The AAA Foundation’s mission is to prevent traffic deaths and injuries by conducting research into their causes and by educating the public about strategies to prevent crashes and reduce injuries when they do occur. This research is used to develop educational materials for drivers, pedestrians, bicyclists and other road users. Visit www.AAAFoundation.org.

AAA Washington Media Contacts

Kelly Just | 425-647-1594
Jennifer Cook | 425-301-9075
Twitter: @AAA_Washington
Facebook: AAA Washington

Interested in planning your next road trip with AAA Washington? Call your travel agent directly or your nearest AAA store to get pro tips, TripTik maps, and more. Find more Pacific Northwest scenic drives and road trips.

Share this post

Media Contact

Jennifer Cook
Senior Manager, Corporate Communications
425-301-9075
JenniferCook@aaawa.com

Kelly Just
Public Affairs Manager
425-647-1594
KellyJust@aaawa.com

Location
Bellevue Corporate Office
3605 132nd Ave. SE
Bellevue, WA 98006

Related Stories

Discover More

Find more ways to get the most out of your travel experience