What You Thought You Knew About MPG Ratings Is Probably Wrong

Do you remember me telling you that advertisements lie, how the marketing people (as well as the product manufacturers themselves) think you’re a sucker and how their goal is to target gullible people who believe everything they see and hear? Well, it’s still true, and nothing is going to change that. This time, my ire wasn’t drawn to companies claiming to be the “best” or “highest quality” or any other subjective claim. No, lately I’ve been more annoyed specifically with car companies and their practices for pitching their automobiles among stiff competition. My beef with them centers on their non-stop talk about how you should buy their cars because of their fuel efficiency ratings. Contrary to what many people believe and what we are allowed to think, the government doesn’t actually run the tests that determine the fuel economy advertised by car companies.

 

The thing that really gets me is that in all of the advertisements I have seen and heard, the number being used is the estimated highway mileage estimate. The way it is presented, it is being made to sound like the higher of the estimates is what you can expect to get when you purchase a particular car. Never mind the fact that a more moderate figure is readily available (the combined mileage estimate), but the big issue I have is that not only do car ads misuse the published estimates, or the fact that they make the figure they throw out there seem like a solid guide, but mostly the fact that most don’t even mention the term “estimate”, nor do they mention the biggest fact of all…

 

Let’s start with a simple fact: 

The auto manufacturers are the ones that determine fuel economy ratings

 

Yes, what you just read is 100% true. There is no independent lab tests or specialized third party firms that do the testing. It is the manufacturer of a vehicle that creates these estimates. And, in most cases, the tests are done on pre-production models, and not even on the exact models that come off of the line and to the dealerships–the ones you will actually be buying. The federal government, by way of a joint venture between the Department of Energy and Environmental Protection Agency, established a website to educate consumers on fuel economy and to help them make informed choices on the matter (as well as maintain their vehicles). It also provides standardized guidelines for testing, but it’s active involvement essentially ends there. When they are done with the tests, the auto manufacturers will send their reports to the agency, which then will review only 10-15% of the results.

 

Faulty assumptions in testing phases

First, this key piece of information essentially results in your having approximately a 1-in-10 of purchasing a vehicle that was verified as having the same fuel efficiency rating as is advertised. It also means that there can be significant deviations between your actual experiences and those estimates. The biggest reason is the fact that any number of events can happen between the testing phase and the end of the production process which can change these estimates. Think of it like a movie with bonus deleted material and extended scenes–not everything makes it to the final product completely intact, sometimes things are removed, added, or changed during the production process. The same can happen during the manufacturing process of any item. There is always room for change or improvement, and there is no guarantee that the models which are shipped for sale are the exact specifications of the ones used in pre-production testing.

 

Secondly are the ways that the tests are conducted: inside a lab, with the car on a dynamometer simulating “typical” trips. All this means is that they put the car on rollers while the car is being driven at a speed determined by the simulator program. Variables such as temperature, wind resistance, and more recently the use of air conditioning are then accounted for by the use of mathematical supplementation. It is a purely speculative means of testing, while at the same time giving consumers false expectations and incomplete information since much of this is not common knowledge.

 

 

Impact on you as a consumer

What does this mean for you? Well, for starters, it means that you will most likely never experience the same mileage ratings in terms of fuel economy that the window stickers claim on new cars. In fact, since the testing methods changed in 2008 which lowered estimates across the board, it became even more difficult to shop for used cars which were tested using old, outdated standards. The reasons for variances between actual and estimated fuel economy are significant and very important to understand.

 

The basic premise of these fuel economy estimates is a 55/45 split in terms of the percentage of highway/city driving. In essence, these numbers can skew the picture greatly depending on where you live. People who live in metropolitan areas with heavy traffic during most of their drive time will see greatly reduced results whereas those who do most of their driving on open highways with little impediments will see opposite results. Fuel is burned more efficiently at constant speeds rather than continual stopping-and-starting, so the traffic patterns play a significant role in the results one would see in real world scenarios.

 

Another factor that is not specifically factored into the estimates is the style of driving. Those who have what is known as a “heavy foot” will see reduced fuel economy as the amount of gas used to accelerate at an abrupt rate is greater than a gradual increase in speed. Also of importance to fuel efficiency is the manner of activity. Those who make frequent stops to complete driving tasks requiring the disengaging, then reengaging of the engine will also see diminished fuel efficiency, as an engine burns fuel more optimally when properly warmed up.

 

Weight and accessories play increasingly important roles in fuel efficiency as well. With more and more electrical components being included in cars, such as large displays, touch screen navigation, built-in monitors, etc. the less efficient fuel will be used. Even carpooling can have a negative impact on fuel economy. While being touted as an environmentally friendly transportation method, it may be more costly to the individual doing the majority of the driving, as increased weight requires more fuel to move the care at the same rate of speed as when driven alone.

 

Solutions to the problem

It’s pretty difficult to return a car if you realize it is not getting the fuel economy you thought it would when you originally bought it. There is no way to take it home for a 30 day home trial like you can do with some other consumer products. Fortunately, there are a few ways to protect yourself. One way is to check out what others are saying about their own fuel economy results. This resource is provided for people to report their own real-world results, and edmunds.com states that the reports are fairly accurate and reliable. Another way to go about it would be to check out independent research authorities like Consumer Reports, or auto & financial magazines that run their own tests on vehicles. Along those same lines, you can ask people who have purchased the same vehicle you are considering. Although the last two methods still leave room for error, as personal driving styles will vary it is still better than not having any other resources other than the figures the auto manufacturers provide.

 

This post was featured in Carnival of Personal Finance: The Color Wheel Edition

  • http://www.beatingbroke.com/ Beating Broke

    Unless you’re buying new (and why would you?), doing your research on the models that you’re looking at and the expected fuel efficiency (as reported by friends and other drivers) is the only way to know for sure what you can expect.  Like you said, there are just too many variables to know where you’ll sit on the spectrum.

  • http://www.beatingbroke.com/ Beating Broke

    Unless you’re buying new (and why would you?), doing your research on the models that you’re looking at and the expected fuel efficiency (as reported by friends and other drivers) is the only way to know for sure what you can expect.  Like you said, there are just too many variables to know where you’ll sit on the spectrum.

    • http://www.dollarversity.com Eric J. Nisall – DollarVersity

      I prefer to buy new.  Less headaches, worry, and maintenance are worth the money.  I’m far from frugal/cheap [depending on how one defines each] and would rather choose an economical new car as opposed to an old car that I can pay for with the bills in my wallet just for the sake of not having payments, but having to maintain it regularly (which most likely would offset much of the cost savings).  

  • http://www.jaicatalano.com/ Jai Catalano

    But isn’t that always the case??? People abuse numbers all the time to appear one way that benefits them. Calories come to mind…

  • http://www.jaicatalano.com/ Jai Catalano

    But isn’t that always the case??? People abuse numbers all the time to appear one way that benefits them. Calories come to mind…

  • http://www.jaicatalano.com/ Jai Catalano

    But isn’t that always the case??? People abuse numbers all the time to appear one way that benefits them. Calories come to mind…

    • http://www.dollarversity.com Eric J. Nisall – DollarVersity

      Actually, when it comes to calories, I think the only ones manipulating the numbers are the people counting them.  Calories are a calculable measure of energy, so if it’s reported by a restaurant or on the package of a food item, it has to be the real number.  MPG ratings are just the manufacturers way of telling people that they are idiots, and blatantly blow smoke up their collective asses.

  • http://moneyqanda.com Hank Coleman

    This are great points about MPG. Like Jai said, statistics are typically massaged in order to make someone’s case. I’m always blown away that more people have not heard about how the car manufacturers manipulate the MPG numbers.

  • http://moneyqanda.com Hank Coleman

    This are great points about MPG. Like Jai said, statistics are typically massaged in order to make someone’s case. I’m always blown away that more people have not heard about how the car manufacturers manipulate the MPG numbers.

    • http://www.dollarversity.com Eric J. Nisall – DollarVersity

      I think the majority of the public just wants to be spoon fed information, even if it is crap, rather than take the time and energy to do independent research.  It’s as simple as that.  All of the information is out there for anyone to find…if they took the initiative to try.

  • http://www.ontargetcoach.com/ Brent Pittman

    Seems there should be an app for finding true MPG then? 

    • http://www.dollarversity.com Eric J. Nisall – DollarVersity

      A lot of the newer cars offer that feature in the instrument panel.  It basically calculates the fuel efficiency of that particular tank or trip, or whatever standard the owner wants to use.  Of course, if people are against new cars, then they will not have access to it for 10 or 15 years when these models become the types that the frugal tend to purchase.

      The problem with calculating MPG is that it isn’t a scientific formula.  If you have drastic weather changes, then your efficiency from season to season will change.  The same is true if you have kids and your driving habits change over the summer compared to the spring and fall when they are in school.  There really is no way to say what the efficiency for any vehicle will be with any certainty until you look at it in hindsight.

    • http://www.dollarversity.com Eric J. Nisall – DollarVersity

      A lot of the newer cars offer that feature in the instrument panel.  It basically calculates the fuel efficiency of that particular tank or trip, or whatever standard the owner wants to use.  Of course, if people are against new cars, then they will not have access to it for 10 or 15 years when these models become the types that the frugal tend to purchase.

      The problem with calculating MPG is that it isn’t a scientific formula.  If you have drastic weather changes, then your efficiency from season to season will change.  The same is true if you have kids and your driving habits change over the summer compared to the spring and fall when they are in school.  There really is no way to say what the efficiency for any vehicle will be with any certainty until you look at it in hindsight.

  • Maggie@SquarePennies

    Hi, Eric!  I like to ask people who own the cars what kind of mpg they get.  It’s not scientific either, but it helps.  Our VW Golf gets about 40 mpg on the highway & maybe 35 around town.  It’s a small car, but very comfortable.  Also it holds a lot of stuff!  Our Sprinter van seats 10 & gets about 25 mpg on the highway.  Both are diesel, and both have been reliable vehicles.  Hope that helps somebody.

    • http://www.squarepennies.blogspot.com/ Maggie@SquarePennies

       Also it’s good to check at Edmunds.com for the “true cost of owning” any vehicle you are thinking of buying.

  • http://www.vaerdi.com/penge-snak/ Crystal @ Vaerdi

    I just use the Estimated MPG results as a very general guide to what car makes better mileage than some other car.  I like going to KBB.com, finding reviews from areas like mine, and seeing what the real MPG’s look like from there.  :-)

  • http://www.moneybeagle.com/ Money Beagle

    Both of our cars have built in gauges that allow you to track MPG.  I have a rough idea of what we get in both cars based on that, not really on the sticker.  What they put on a sticker is from data collected in situations that varies completely different from what anybody uses in the real world.  I don’t think they’re trying to be manipulative, just using a different system to make their estimates that they hope will fall within range of a majority of people buying that particular automobile.

  • http://untemplater.com/ Untemplater

    Things are never as good as advertised.  The battery life on my laptop and phone are perfect examples!  I always read a lot of reviews before I buy anything to get a better idea of what the product is really like.

  • http://www.nextpay.com/offshore_processing.php Belinda Ramirez

    Hello Eric, kindly delete this comment as well as the first three comments I made. I didn’t know what was the problem. Please leave out the one before this. Thanks much!