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Sign-up to the MPG Monitor campaign

MPG Monitor logoIf there is one issue that dominates your feedback above all others,
its the discrepancy between official fuel economy (in miles-per-gallon or MPG) and the fuel economy you achieve driving on real roads.

In short, few of you are able to match the published (combined) MPG figures as stated by the manufacturer. When it comes to cars, it seems that for fuel economy, it never 'does exactly what it says on the tin'.

We sympathise with your position and experience and have started the MPG Monitor campaign to make a case for a changing the current fuel economy test. Sign the e-petition and give us your views, and we will lobby the UK Government and manufacturers on your behalf.

Read about new research that shows how car makers manipulate the official MPG tests to produce over-optimistic fuel economy data.



What's the issue with 'official' MPG?

The problem with the official MPG arises due to the limitations of the New European Drive cycle which is far from a real-world test cycle - but generates all the official data.

The so-called 'New European Driving Cycle' (NEDC) is used to generate the familiar 'urban', 'extra-urban' and 'combined' official figures. Performed on a rolling road, these tests are used for emissions certification of light duty vehicles in Europe, and from which fuel economy figures are calculated (rather than measured).

While vehicle technology has significantly advanced in the past decade, the test procedure is increasingly unrepresentative of real-world driving, and is conducted with all ancillary loads (such as heating, air conditioning, lights, and heated windows) turned off – air conditioning alone can worsen fuel economy by 20-30%. Due to these factors, the discrepancy between the 'official' and real-world data is widely acknowledged; the Energy Saving Trust recommends an adjustment (on average) of around 15%.

Moves are afoot to replace the NEDC, but not until 2014 at the earliest. One option on the table is the Artemis Driving Cycle (ADC) which consists of four drive cycles (urban, rural road, two motorway) all of which include the rapid changes in speed typical of driving on real roads.

With others in the industry, we want to lobby the UK Government and manufacturers on your behalf about this issue. If you would like to join the campaign, sign the e-petition, and leave us a comment on the 'post-it' wall.


Sign the MPG Monitor e-petition

MPG Monitor logo

Sign the MPG Monotor e-petition and help us lobby the UK Government and manufacturers about this issue.

The more signatures we have on the petition, the stronger will be our case.


We value your support – don't forget to leave us a comment on the 'post-it' wall.


Find out more about official and real-world MPG

The 'New European Driving Cycle' (NEDC) is used to measure 'urban', 'extra-urban' and 'combined' official figures. Performed on a chassis dynamometer (a rolling road), these tests are used for emissions certification of light duty vehicles in Europe, and from which fuel economy figures are calculated (rather than measured).

Two test cycles make up the NEDC, the first representing urban or city driving (4.1 miles, 780 seconds), with the second simulating motorway conditions (7.0 miles, 400 seconds). To make the tests repeatable, cycles are conducted on a dynamometer which is set up to represent a flat road, the rollers providing resistance to mimic aerodynamic drag (a fan blows over the car to provide airflow for air intakes). Lookup tables are applied to account for different body shapes, allowing models sharing the same chassis to be tested at the same time.

NEDC test cycles

During the tests, exhaust emissions are collected and weighed to measure the total CO2 and other regulated emissions (such as NOx and particulates). Based on the carbon emissions and fuel type, fuel economy values are then calculated.

Not only are the two test cycles out of date (cars were lighted and less powerful than they are now), the tests are no longer representative of real world driving, which is now faster and more aggressive. The tests are also conducted with all ancillary loads (such as heating, air conditioning, lights, and heated windows) turned off – air conditioning alone can worsen fuel economy by 20-30%.

Artemis test cycles

Moves are afoot to replace the NEDC, but not until 2014 at the earliest. One option on the table is the Artemis Driving Cycle (ADC) which consists of four drive cycles (urban, rural road, two motorway) all of which include the rapid changes in speed typical of driving on real roads.

What's not yet being considered, however, is an alternative approach to the use of dynamometer testing. With a digital and information revolution going on, testing in the field (as well as in the lab) is now a real option.

To help us lobby the UK Government and manufacturers on your behalf about this issue, sign the e-petition, and leave us a comment on the 'post-it' wall.

Read about new research that shows how car makers manipulate the official MPG tests to produce over-optimistic fuel economy data.


Post a message on the 'post-it' board

Post a message

Next Green Car would like to know what do you think on this issue.

Is it enough that the official combined fuel economy is for comparison? Or should the test values be closer to real world MPG? How does your fuel economy compare with the official figures?

Leave a comment below... your message will also appear on the 'post-it' wall after a few minutes.

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