Navigant Research Blog

Getting the Most MPG

David Alexander — October 23, 2012

In February 2012, a disgruntled customer won a small claims suit against Honda, claiming that the Civic Hybrid she bought never achieved the advertised 50 mile per gallon (mpg), which was the figure Honda claimed from the statutory EPA tests it is required to run.  The ruling was overruled in May by the Los Angeles County Superior Court, but spurred a number of additional claims in courts around the country.  The case emphasized the need for vehicle manufacturers to manage their customer expectations.

The EPA-mandated test was developed as a way for customers to compare vehicle economy by establishing a standard, supposedly typical, drive cycle for all vehicles.  If the cycle does not match your route and the way you drive, though, you won’t achieve the advertised number.   It was never intended to be a figure that all drivers would achieve.  (This factor is discussed in our recent report, Stop-Start Vehicles; under the EPA testing conditions, eliminating idling does not show any benefit for vehicles equipped with this system.)

Ford discovered this problem with hybrids after the launch of the first hybrid Escape in 2004.  The average driver thought that the technology would magically deliver better fuel economy regardless of how they drove.  So Ford quickly put together an event called the Escape Hybrid Experience to try to educate the owners.  Fortunately these were mainly early adopters who were keen to sign up, and the event was repeated at many locations all across the United States.

The key tactic in driving a hybrid is to make maximum use of the regenerative brakes, and avoid rapid acceleration as much as possible.  Gentle braking captures kinetic energy and stores it in the battery; heavy braking converts that energy to waste heat in the discs just as in a conventional vehicle.  Hybrids typically don’t do well at high speed, when the extra weight of the batteries and electric motor requires more energy to keep moving.  Driven gently, in stop-start traffic conditions, they deliver much higher mpg.

The MPG Marathon

Of course, driving in the recommended manner for hybrids will improve fuel economy for conventional vehicles too.  This was proved recently at an event in the United Kingdom, called the MPG Marathon, sponsored by ALD Automotive and Shell, among others.  In this annual test of driving skill and vehicle efficiency, drivers have to complete a course of 370 miles in normal traffic over 2 days, meeting timing restrictions that mean you cannot win by driving at 10 mph the whole way.  Vehicles must be in current production on the day of the event, and there are various vehicle categories for judging.

While best overall mpg is the goal of the event, the organizers also track the percentage improvement over the official mpg rating from the U.K. government standard test.  The overall winner this year was the Ford Fiesta ECOnetic, a small car with a 1.6-liter diesel engine, which achieved 108.8 mpg on a vehicle rated at 85.6 mpg under the official combined cycle test.  (U.K. gallons are larger than American gallons, but the economy is still impressive.)  Citroën’s Nemo won the van category, with 77.5 mpg.  Full results are on the competition website, but most manufacturers use the event to publicize their vehicles even if they don’t win: Toyota, Peugeot, Ford, Citroën, etc.

The conclusion here is that it’s not just the technology but how you use it that gets results.  And if you learn the correct technique and try hard, you can beat the official figures, and you don’t have to sue the manufacturer.

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