Farley calls Ford’s “Personalized Fuel Efficiency App Challenge” a first step in that direction. Focusing on mobile platforms, app developers will have access to Ford’s OpenXC connectivity research platform to create and test ideas with $50,000 in prize money from the auto maker on the line.

He expects the apps to take into consideration elements affecting real-world fuel economy, such as weather conditions, terrain, traffic congestion and, especially, individual driving styles.

The winning app ultimately would enable drivers to optimize their fuel efficiency and then share their information with others.

“We need to help customers understand the concept of personal fuel economy, based on their own individualized experiences, and give them tools to see, learn and act upon all the information available to know what to expect, how to improve and even offer guidance in their shopping process,” Farley says in announcing the challenge.

David Regan, instructor of advertising, Ad/PR department-Michigan State University, says auto makers face a dilemma when balancing the need to advertise fuel economy against potential lawsuits that could arise if real-world results come up short.

Fuel economy “is one of the core strengths of a smaller-type vehicle,” he tells WardsAuto. “If you take away the numbers, it is not as impactful.”

Regan says it may take some creative copywriting by automotive ad agencies to tout the fuel economy of vehicles without stating numbers.

While lawsuits are one potential pitfall if advertised fuel-economy numbers don’t translate to real-world experience, another is the damage caused to the entire brand, Regan says.

“It puts you in damage control with consumers that are now suspicions of any claims you make about any of your vehicles,” he says. “We buy brands we trust, and if we lose it we may not place investment in that brand.”

Despite the potential dangers of advertising fuel economy, its importance to consumers is profound and the numbers likely still will be touted by the auto makers, says Jack Gillis, director-public affairs, Consumer Federation of America.

According to a recent CFA survey, 88% of car buyers say fuel economy is an important factor in their next vehicle purchase, and most expect an increase in mileage with each new model upgrade.  “So fuel economy is top of mind for today’s car buyers,” Gillis says.

The controversy surrounding Ford and Hyundai mileage claims likely will have little impact on consumer sentiment, he adds, advising vehicle buyers to use EPA fuel-economy labels as a comparison between models and not what they can expect to achieve in real-world driving.

“I think most consumers understand the numbers are best used to compare on a relative basis,” he says. “So while a 37 mpg (6.3 L/100 km) sticker may not get you that, it’s better to purchase that (vehicle) than one with a 30-mpg (7.8 L/100-km) sticker.”

Some observers say a sweeping change to EPA tests may be the only way to achieve accurate real-world mileage estimates. But that option is unlikely, Concerned Scientists’ Anair counters.

“Tests are written into law for fuel-economy standards, so Congress would have to change them,” he says. “The EPA has worked within that constraint over the years to make adjustments, but changing the tests is not trivial.”