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Consumer Reports says it wasn't able to replicate the fuel economy claims of Ford (F -0.7%) in...

Consumer Reports says it wasn't able to replicate the fuel economy claims of Ford (F -0.7%) in informal testing of the Fusion and C-Max hybrids. The magazine calls the real world tests "very good" but falling below the 47 mpg. Automakers have been under a spotlight lately over fuel economy after Hyundai and Kia were found to have exaggerated their claims.
Comments (5)
  • I haven't been following this lately, but I remember a while back that the EPA (I think) mpg estimates were found to be inaccurate because they're calculated based on emissions rather than based on real-world driving. Perhaps this is a similar situation, with the automakers using a different testing method? Again, not in the know, so I'd appreciate insight from someone who does know.
    6 Dec 2012, 04:16 PM Reply Like
  • Great Question!


    All automakers that mean to sell passenger vehicles in the US have five very specific EPA drive cycles for measuring fuel efficiency. They drive the vehicles through all five cycles, in exactly the right way, and with the prescribed accessories on or off (headlights, AC or heater, etc.), measuring the fuel consumed in each cycle, and reporting the results in terms of highway, city, and combined ratings.


    source -


    The five cycles are:


    1. "city" / UDDS consists of starting with a cold engine and making 23 stops over a period of 31 minutes for an average speed of 20 mph (32 km/h) and with a top speed of 56 mph (90 km/h). The test is repeated adding a "hot start" engine cycle, which repeats the "cold start" cycle after a 10 minute pause. The result is then adjusted downward by 10% to more accurately reflect real-world results.


    2. "highway" (HWFET) uses a warmed-up engine and makes no stops, averaging 48 mph (77 km/h) with a top speed of 60 mph (97 km/h) over a 10-mile (16 km) distance. The result is then adjusted downward by 22% to more accurately reflect real-world results.


    3. SFTP US06 is a high speed/quick acceleration loop that lasts 10 minutes, covers 8 miles (13 km), averages 48 mph (77 km/h) and reaches a top speed of 80 mph (130 km/h). Four stops are included, and brisk acceleration maximizes at a rate of 8.46 mph (13.62 km/h) per second. The engine begins warm and air conditioning is not used. Ambient temperature varies between 68 °F (20 °C) to 86 °F (30 °C).


    4. SFTO SC03 is the air conditioning test, which raises ambient temperatures to 95 °F (35 °C), and puts the vehicle's climate control system to use. Lasting 9.9 minutes, the 3.6-mile (5.8 km) loop averages 22 mph (35 km/h) and maximizes at a rate of 54.8 mph (88.2 km/h). Five stops are included, idling occurs 19 percent of the time and acceleration of 5.1 mph/sec is achieved. Engine temperatures begin warm.


    5. Lastly, a cold temperature cycle uses the same parameters as the current city loop, except that ambient temperature is set to 20 °F (−7 °C).


    The EPA even provides the excel calculator for reporting the results:


    SO the question is, who screwed up? Did Ford run the tests wrong, or did they falsify the data? It seems doubtful since the EPA already verified and certified Ford's reported results as valid. Also Ford's recent history with fuel economy has show that they generally fall well within 1 mpg of the EPA quotes in independent validation tests.


    OR, was it Consumer Reports that failed to run the EPA tests correctly and exactly by the book? Or did they run their own made-up test?


    Or was there something wrong with the sample vehicle(s) Consumer Reports used in their tests?


    It will be interesting to see how this plays out in the coming days...
    6 Dec 2012, 07:26 PM Reply Like
  • Also, hybrids are especially sensitive to how you drive them - "your mileage may vary". If you go really easy on the accelerator pedal, and go smoothly and gently on the brakes to efficiently recapture the energy, the car may run in electric mode for quite some ways until the high voltage battery is drained. But if you step on it just a little harder, the engine starts and does the work.


    The difference in resulting mpg in a hybrid is huge depending on how much time is spent in electric mode. Basically you get infinite mpg as long as you stay in electric mode, but when the engine is running you may get closer to 20 mpg for exactly the same segment.
    7 Dec 2012, 12:56 PM Reply Like
  • UPDATE ...


    DETROIT (AP) -- Ford said Friday that it's talking to the government about the fuel economy of its hybrid cars after a report suggested they're falling short of targets.


    Consumer Reports said last week that Ford's new C-Max hybrid didn't meet the published fuel economy of 47 miles per gallon, averaging 38 miles per in the magazine's testing. Other hybrids — including the Ford Fusion and Toyota Prius V — have also fallen short in the magazine's tests.


    Ford said it followed the Environmental Protection Agency's guidelines when it set its fuel economy standards. But the EPA's hybrid tests don't exactly mimic real-world driving. For example, Consumer Reports said it measures highway fuel use for a car going 65 miles per hour, but the EPA's highway test speed averages 48 mph.


    Ford's global vehicle development chief Raj Nair said the way owners drive their hybrids can also affect performance. For example, driving a hybrid car 75 miles per hour, instead of 65 miles per hour, can cost the driver seven miles per gallon, Nair said. Hot or cold temperatures can also affect the numbers.


    Nair said Ford is talking to the EPA to see if the agency needs to change the way it tests hybrids. The EPA said Friday that it is reviewing Consumer Reports' results.
    14 Dec 2012, 08:17 PM Reply Like
  • Further update - Consumer Reports finally 'fesses up!



    It all makes sense now. Ford's new hybrids are designed run in pure EV mode up to 62 mph (100 kph), for as long as there is reasonable state of charge on the high voltage battery. The EPA "highway" test includes some time at speeds that are below 62 mph (thus potentially running in pure EV mode) and some time at speeds above 62 mph (hybrid - gas engine plus EV), so you get a blend of both, thus 47 mpg.


    Consumer Reports' highway test runs exclusively at 65 mph, so there is zero time in "pure EV" mode: the gas engine is running for the entire time, thus achieving 38 mpg. If Consumer Reports ran the test at 62 mph instead of , then the measured fuel efficiency would have been essentially "infinite" mpg, because the gas engine would not have been running.


    It is pretty stunning that it took Consumer Reports so long to 'fess up to essentially "cheating" on the EPA's highway test, and then slandering Ford.
    15 Dec 2012, 09:55 AM Reply Like
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