It's been a rough time for the official fuel economy figures for the Ford C-Max Hybrid. When the car was released in 2012, Ford made a huge deal about how it would beat the Toyota Prius V, which was rated at 42 combined miles per gallon, 44 city and 40 highway. The Ford? 47 mpg across the board.

How did Ford come to this place, where its Prius-beater turned into an also-ran?

Well, after hearing customer complaints and issuing a software update in mid-2013, then discovering a real problem with the numbers last fall and then making a big announcement last week that the fuel economy ratings of six different 2013 and 2014 model year vehicles would need to be lowered, the C-Max Hybrid has ended up at 40 combined, 42 city and 37 highway. In other words, the Prius trumps it, as daily drivers of those two vehicles have known for a long time. The changes will not only affect the window sticker, but also the effect that the C-Max Hybrid (and the five other Ford vehicles that had their fuel economy figures lowered last week) have on Ford's compliance with greenhouse gas and CAFE rules for model year 2013 and 2014.

How did Ford come to this place, where its Prius-beater turned into an also-ran? There are two technical answers to that question, which we've got below, as well as some context for how Ford's mistakes will play out in the bigger world of green vehicles.

2013 Ford C-Max Hybrid

Let's start with Ford's second error, which is easy to do since we documented it in detail last year (the first, needing to do a software update, was also covered). The basic gist is that Ford used the general label rule (completely legally) to test the Fusion Hybrid and use those numbers to figure out how efficient the C-Max Hybrid is. That turned out to be a mistake, since the two vehicles are different enough that their numbers were not comparable, despite having the same engine, transmission and test weight, as the rules require. You can read more details here.

Ford's Said Deep admitted that the TRLHP issue is completely separate from the general label error from last year.

Now let's move on to last week's announcement. What's interesting is that the new recalculation of the MPG numbers – downward, of course – was caused by a completely separate issue, something called the Total Road Load Horsepower (TRLHP). Ford's Said Deep admitted to AutoblogGreen that the TRLHP issue had nothing to do with the general label error from last year. "When we retested [the C-MAX Hybrid] last summer, we had not yet run the production vehicle validation tests that revealed the error related to how we correlate wind tunnel results into the TRLHP model," he said.

So, what is that model? Well, it's not easy to understand, but two detailed places to dig in are here and here (PDF). Ford's announcement yesterday said that:

TRLHP is a vehicle-specific resistance level used in vehicle dynamometer testing that determines fuel economy ratings. TRLHP is established through engineering models that are validated through vehicle testing, including physical track tests referred to as coastdown testing.

The EPA described TRLHP to AutoblogGreen this way:

When using the dynamometer testing, certain factors/inputs need to be accounted for so that the test is as accurate as possible in reflecting real-world conditions. One of these factors is TRLHP. The TRLHP is derived from an engineering model and is validated from vehicle track testing. To calculate it, one must account for different variables such as crosswinds, aerodynamics, and tire friction.

In Ford's case, it wasn't just the TRLHP number that was off. Raj Nair, Ford's fall guy for hybrid mpg overstatement, told reporters that, "we do a physical wind tunnel test, and then use a correlation factor to enter that into the engineering model – which is then the total load horsepower test. The error was in the correlation factor in the model."

2014 ford fiesta

It's not only the C-Max Hybrid that was downgraded yesterday. The C-Max Energi, Fusion Hybrid and Energi, the Lincoln MKZ and most versions of the 2014 Fiesta were also acknowledged to be less efficient than previously stated. Despite all of these revisions – plus the Hyundai/Kia mpg errors – the EPA told AutoblogGreen that it doesn't expect that we'll see more changes in the future:
We generate over 1200 labels each and every year, and these three re-labelings represent a tiny fraction of that amount. With the majority of consumers achieving or bettering the label fuel economy estimates, based on consumer data provided to and other websites, we are confident with vehicle test results and fuel economy label values.
Despite the wording of the EPA's press release that made it sound like the government agency pressured the automaker to change the MPG rating, the EPA confirmed that Ford came to the government with the news:

On March 28, Ford alerted EPA that they had identified a possible error affecting their fuel economy values. EPA immediately began working with Ford on an extensive re-testing program to correct the error, overseeing Ford's fuel economy tests, and also conducted independent testing at our Ann Arbor lab to confirm Ford's results. Under EPA regulations, Ford is required to correct fuel economy labels on affected vehicles within fifteen days.

Electric vehicle supporter and star of Who Killed The Electric Car? Chelsea Sexton said that Ford deserves credit for the, "the straightforward announcement, apology, and goodwill payments" and that the real interesting issue will be, "how the increased focus on these numbers affect EV range claims used by automakers in marketing, if not on Monroney stickers. Given the consequence to new drivers and, ultimately, the success of EVs, overly optimistic range numbers are the perfect example of 'just because you can, doesn't mean you should'."

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    • 1 Second Ago
      • 1 Year Ago
      Well, after last software update to allow up to 70mph in electric mode, getting 45MPG mixed in our 2013 C-Max hybrid. No complaints.
        • 1 Year Ago
        Those stats tell alot about your driving style and not much else...Im convinced you'd be getting 60mpgs in a Prius ;-)
          • 1 Year Ago
          Except I would have to 'drive' a Prius. That's a penalty box on wheels. Driving style hasn't changed since getting the car, software update made a big difference. Since interstates are 60mph here, and everyone drives 65+, electric mode cutting off at 62mph verses 70+ makes world of difference.
      • 1 Year Ago
      Ford is a really big company. All this is BS to backtrack on what they did. They played the game of knowing there was a problem but ran with it so they could advertise the higher MPG. To an extent all large and small companies do it with advertising. However, Ford calculated out that having the high initial number would stick in their customer's head. I'd bet that even now there are people that will tell you the C-Max gets 47 MPG. If they had just fudged the number then there wouldn't have been such a big backlash. They wanted to beat Toyota and paid the penalty.
      • 1 Year Ago
      My last tank got 138 mpg. I'm happy. Very reliable car
      • 1 Year Ago
      It seems to me that TRLHP is a contorted way of naming the required power to have the car travel at constant speed, said power increasing at higher speeds. In other words, they screwed up their testing.
        • 1 Year Ago
        Correct on all fronts. You calculate the power required to travel at speeds, then you punch those load figures into the dynamometer when running the tests. If you get a low TRLHP, then the engine works less hard during the test and you get better mpg. And Ford knows it. They did it on purpose. Why it is done covered pretty well at this link: And it indicates that recently (as mpg as been more important), the gap between the proper value that should be used and the ones the car companies determine has been increasing. In other words, the companies have been cheating more and more.
      • 1 Year Ago
      I'm in the unique position to compare the MPG of the plug-in Prius to the plug-in C-Max. I have owned them both and am now driving (and loving) the C-Max. I use it as a daily driver with each way being around 10 miles. I am getting MUCH better MPG with the C-Max because of issues that are not discussed very often. 1) Prius always starts engine when cabin needs heat. It could not be preheated while plugged in. The C-max can be preheated or pre-cooled while plugged in and therefore will not start the engine unnecessarily. 2) I can get about 20-23 miles on EV with the C-Max so I can do many more around town trips without ever starting the ICE. After 1300 miles, the C-max has over 3/4 tank of gas left in it. If you put a lot of miles on your car, the Prius will be better. On the other hand, the C-Max is a far superior car in every way. ie: comfort, handling, cornering, passenger room, upscale interior etc. The Prius does have more room for stuff when you fold down the rear seats but my costco runs have not been hindered by the C-Max's room. I would not go back. The Prius is basic transportation with good MPG. I'd much rather be driving the C-MAX (and in my case getting much better gas mileage).
      • 1 Year Ago
      Anyone who believes advertised economy figures is crazy. I thought it was general knowledge that advertised MPG numbers are usually about 20% higher than in real life? The fact that manufacturers can advertise such blatantly unrealistic numbers is a different issue.
        • 1 Year Ago
        Sure, trust but verify. But you're flat out wrong about your general knowledge. The EPA numbers are usually off by less than 10%, and sometimes they're wrong in your favor. Ford managed to hit 20%. They lied. In bad faith. EOF.
        • 1 Year Ago
        My Subaru is spot on at 27mpg highway. My Prius is getting about 2-4mpg more than advertised. Yet, i had a CMax Hybrid as a rental, granted it was at about 1000feet more elevation than i normally drive, i was getting about 37-38 hand calculated mpg and drive mostly highway. Yet in my 2011 prius with 3 guys in it, driving 70-80mph all highway,i got 48mpg hand calculated. Normally by myself, i get 50-52mpg average hand calculated over a full tank The EPA changed the rating standards in 2008, it was suppsoed to be more representative, and i think they did a decent job. But obviously there is room for cheating.
      • 1 Year Ago
      That may be true, but why wouldn't Ford want to make sure their numbers were relatively accurate, especially for high profile vehicles like hybrids? This just makes them look bad and momentarily takes the spotlight off of GM.
      • 1 Year Ago
      All garbage. They lied. Let's take a step back from all the technobabbly excuses like "TRLHP", "correlation factor" and "dynamometer testing". How is it possible that a bunch of high-paid, well-educated managers and engineers signed off on these bogus figures without realizing that—wait a minute—forget the ridiculously complex computer models and calculations and simulations, in real life the car actually can't come anywhere close to the 47 MPG figure? Any person driving that car with a full tank of gas would realize something was really wrong with the numbers they got. Why did the mad scientists in France and Switzerland built a monstrous 27 km-long machine underground called the Large Hadron Collider? It's because to figure out whether something is real, you have to test it for real, fools.
      • 1 Year Ago
      While I'm not usually one to advocate increased government regulation, it's clear that the auto industry is incapable of performing their own fuel efficiency testing/labeling. Have the EPA run every new car around a test track for a full tank of fuel according to a prescribed speed schedule that corresponds to the average American's commute. Record that number and stick it on the window sticker. Can't be any worse than the mess we have now.
        • 1 Year Ago
        Even better - take 10 cars, off the line and give they to drivers in different parts of the country. Have them each dive 1000 miles and then download the data. The number will be the actual mileage you will get owning the car in real world, mixed driving, conditions.
        • 1 Year Ago
        We gave them a chance to 'self-regulate' . . . and they abused it. They should lose their privileges. At the minimum, all Hyundai and Ford cars should be EPA tested.
        • 1 Year Ago
        The EPA thinks people should be driving 55mph, like they should. The numbers work at those speeds.
        • 1 Year Ago
        That wont work because of variable conditions especially the weather. Temp, Humidity, windspeed, wind direction, and tire all play major factors. Its even more amplified now because of turbos.
          • 1 Year Ago
          In my field (aerodynamics) we correct everything to coefficients that are independent of environmental variables. The EPA could correct for air density and wind, tires are a non-issue (test with the OEM tires), and humidity doesn't have a first order effect. Their error couldn't be more than Ford's >15% error.
        • 1 Year Ago
        @Matt helped to create awareness for this...
      • 1 Year Ago
      And filling the tank!! LOL
      Gregg Fischer
      • 6 Months Ago

      We just received a check from Ford Motor Company. What I'm about to disclose concerns how to fight a car manufacturer to buy back their car when it's a lemon. In our case, it was Ford Motor Company (specifically Lincoln) and their misrepresentation of the 2013 Lincoln MKZ. We traded in a 2012 MKZ for the 2013 MKZ Linclon Hybrid. While the 2012 MKZ delivered the stated MPG, the 2013 MKZ Hybrid was delivering 10 MPG less than what was stated on the sticker (45 Combined MPG). We purchased the car form Alex Karras Lincoln in Bradenton, Florida. The car was delivered dirty and we later found out had not had Pre-Delivery Inspection. Within the first 200 miles of driving, the center console blew completely and it took weeks to the the part from Mexico. During the ensuing 18 months we were given every excuse as to why the car was not achieving the stated 45 Combined MPG. The reasons were as follows:

      1- You don't know how to drive a hybrid.
      2- The electrical problems your carecontributed to the lack of MPG.
      3- The computer needs to be reset (six times) think Control. Alt and Delete and you'll get the idea.
      4- You're not driving the car correctly.
      5- The computer needs a current update.
      6- Do you know how to drive a hybrid?
      7- The latest update from Ford Motor Company was designed to increase the MPG. After that update we got 2 MPG less than before the update.
      8- The computer needs to be disconnected. They disconnected the battery and re-connected.
      9- Are you sure you know how to drive a hybrid? Do you know how to use the braking system to increase the battery life?
      10- We took your car on a test drive for 9 miles and we got 42 MPG with the air on and 50 MPG with the air off.

      #10 was the last insult that Ford Motor Company could throw at us as Ford itself reported that they misstated their OWN EPA results and stated the car would never get over 37 MPG. See article below:…/ford-lowers-fuel-economy-ratings-o…

      So, we sued Ford Motor Company under the Florida Lemon Law and guess what? We won! In fact, if you didn't cash your gas gift card for $1050.00 (which is what they handed out to 2013 MKZ Hybrid owners) you may still have a claim and should go after Ford for their outright lying to you as a consumer of their products.

      You can file a Lemon Law claim yourself (you do NOT need an attorney to do so) or you can retain and attorney and the most they'll from you is $2500.00 if you settle with the auto manufacturer before it goes to Arbitration or court. You are required to file a claim through BBB Autoline (and while that group is a total waste of your time and effort as they always seem to deny a claim) your last step is to stick it out with the Florida Attorney general's Office and see your case through.

      Document everything that goes wrong with the car. Use your cell phone to make videos, take images and even record what the service people are saying (you must tell them you're going to record your conversation with them before doing so). Document! Document! Document! The car manufacturer counts on you being inept in presenting your case. You can bring them to their knees by submitting CD's of images, videos and written reports of their unwillingness to do right by you to the Arbitration Board.

      • 1 Year Ago
      Why is it that these automakers always make "mistakes" than make the MPG higher? I don't remember anyone ever revising their fuel efficiency because they accidentally made it too low.
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