Motor Vehicle Fuel Efficiency

Advertising Just EPA MPG Highway Numbers Is Deceptive

CFA and CAS Call on the FTC to Prohibit the Use of Only City or Highway EPA MPG Numbers in Advertisements—New CFA Survey Indicates Consumers Believe Highway only is Deceptive

Washington, D.C. – In comments filed with the Federal Trade Commission on September 7, 2016, the Consumer Federation of America and the Center for Auto Safety called on the FTC to prohibit the use of only highway or city EPA MPG estimates in advertising.  The FTC is reviewing advertising guidelines governing the use of MPG references in advertising and, so far, has found that allowing car makers to promote only a highway estimate is fine.

“We believe that allowing the promotion of just the highway EPA mileage estimate is misleading and deceptive for a number of reasons,” said Jack Gillis, CFA’s automotive expert and author of The Car Book.  “First of all it is impossible to infer overall fuel economy performance from just the highway (or city) EPA MPG rating. Our analysis of over 1000 EPA mileage ratings for the 2016 vehicles demonstrates that there is no relationship between a particular highway rating and its corresponding city or combined rating.”  For any single highway number, the corresponding city number can vary by as much as 17 MPGs with 14 different ratings. As such, it is literally impossible for a consumer to make an accurate inference of the associated city or combined MPG with the FTC permitted highway only MPG figure.

As one of the many examples CFA discovered, both the Hyundai Sonata SE and the Toyota Camry Hybrid XLE/SE get the same 38 highway MPG rating.  However the Sonata gets only 25 MPGs in the city whereas the Camry gets 38—a 13 MPG difference.  When you compare the combined MPG rating (a number which closely approximates actual use) for each of the vehicles; there is a 10 MPG difference.   By allowing car makers to simply promote just the highway MPG, consumers would easily be deceived into believing that the fuel efficiency of the Sonata and Camry was the same.

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Because it is simply impossible for consumers to impute this very significant difference between two vehicles, using just the FTC allowed 38 MPG highway number, is clearly deceptive.  There are many, many other similar combinations among the vehicles which demonstrate the misleading nature of allowing the use of the highway only rating.

The following chart demonstrates the range of MPG ratings associated with each of the highway ratings available on this year’s models.

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Deceptive Disclosures Will Cost Consumers

Depending on just the highway number can have a serious negative impact on consumer pocketbooks and household budgets.  For example, using today’s $2.12[1] per gallon of gas and a typical 15,000 annual driving cycle, the 10 MPG difference in the combined rating between the Chevrolet Impala Limited and the Lexus NX 300h, each having the same highway rating of 31 MPG can cost consumers $452 per year. If gas goes up to, say, $3.15, the consumer cost will be over $671.

CFA Survey: Consumers Believe Promoting Just the Highway EPA Estimate is Deceptive  

The Consumer Federation of America commissioned a national consumer opinion survey on August 18-21, 2016.[2]  64% of respondents indicated that it is misleading to allow manufacturers to advertise only the highway EPA mileage number.  In addition, 43% of respondents indicated that including both the highway and city number in advertisements, as opposed to just the highway number, would affect their behavior.  That adding the city number caused a behavior change in over two-fifths of the respondents indicates the importance of presenting both numbers.  “This behavior change is one reason why car makers don’t want to provide both city and highway numbers,” said Gillis.

When asked to indicate which of the MPG disclosure possibilities auto advertisers should be required to include if making a fuel economy claim, 65% said that both the city and highway estimates should be required, while 23% chose the combined estimate.  Only 6% preferred just the city number and only 3% preferred just the highway estimate.  Simply put the vast majority (nearly 90%) want either both numbers or the combined rating.

FTC Research Provides the Best Evidence of the Need for Full Disclosure Consumers Need the Full MPG Story to Avoid Being Deceived

“What is particularly disconcerting is that the FTC has essentially determined that consumers believe that they can infer expected performance from a single number,” said Gillis.  Because most of the time there is no relationship between city and highway, consumers simply can’t make the rational assumptions claimed by the FTC, even if they think they can. Thus, advertisers need to use both city and highway, the combined, or all three EPA MPG numbers when promoting fuel efficiency performance. NOTE: Because the combined does consider the varied relationships between highway and city MPGs, it provides consumers with a reasonable basis for vehicle comparison as well as their own expected results.

By allowing automakers to advertise only highway mileage, the FTC not only gives consumers the worst information, it also gives automakers an incentive to game the standards governing fuel economy.  It is counterproductive from both the consumer and public policy points of view.  Presenting both the highway and city numbers, just the combined, or all three should be the only options available to auto advertisers.

Contact: Jack Gillis, 202-737-0766


CFA is a nonprofit association of more than 250 pro-consumer groups that was established in 1968 to advance the consumer interest through research, advocacy, and education.

[1] According to AAA

[2] The survey was a national random sample survey of 1,008 adults conducted by telephone (wireline and cellular) from August 18 to August 21, 2016 by ORC International.  For the full sample, the confidence interval is +/- 3.09%, at the 95 percent level.