There’s some big changes going on in the way that modern new cars are tested for their fuel economy and CO2 emissions, as well as other pollutants.

WLTP will be a new measure for these things, and will also work with plug-in and electric cars, too, which means you can expect more realistic ranges than before.


What is WLTP?

WLTP stands for Worldwide Light Vehicle Test Procedure and it’s the new name and measurement which manufacturers must use to test the efficiency of these vehicles – covering fuel consumption, CO2 emissions, carbon monoxide emissions (CO), nitrous oxide (NoX), as well as the number of particulates.

WLTP replaces the previous way in which these things are measured – NEDC (New European Driving Cycle) which was last updated in 1997, and is therefore outdated.


What’s the benefit?

The NEDC has become outdated as it’s based on procedures drawn up in the ‘80s, and the new WLTP test came into force in 2017.

WLTP will be based on real-driving data, rather than theoretical driving in NEDC, and is therefore expected to reflect more realistic figures that drivers will be able to obtain.

If you’ve ever complained about your car not being able to match its claimed fuel economy figure, this is what WLTP is aiming to sort. Economy figures are expected to be down between around 20 per cent on NEDC stats.

It’s worth noting that the figures are not ‘real-world’ as tests will still be carried out in a lab.


But what are the differences?

The WLTP test will be longer in time and length, and also more flexible than that of NEDC tests.

Whereas the NEDC test was 20 minutes long and 6.8 miles in length and covered just two types of roads, the WLTP will be 30 minutes long, cover 14.4 miles and take into account a mix of conditions – including urban, city, rural and motorway driving.

The WLTP test will also vary depending on the type of vehicle being tested, and will change on account of a vehicle’s power-to-weight class. Whereas the NEDC had a fixed gear shift point, the WLTP test will have different point to change gear according to the vehicle. It will also take into account lower test temperatures than that of the NEDC as well.


Does this affect electric cars and plug-in cars?

Yes, plug-in hybrids (PHEVS) and all-electric cars will also be tested under WLTP rules, which means you can expect more realistic electric-only ranges, and more realistic fuel economy figures on PHEVs.

Hybrids are a little more complex as they will be tested numerous times with various charges on their batteries – from full to empty. This should give a better indication than some of the inflated figures which some manufacturers claim their plug-in hybrids to achieve.


Could my road tax and company car tax increase if my car if found to be less efficient?

While manufacturers have to meet WLTP requirements from September, the figures won’t have to be reported until 2020 as is the complexity testing every engine and trim level of each car.

It’s a confusing and muddled situation (as tends to be the case with politics) but the NEDC figures will still be used as the basis of working out road tax charges and BiK company car tax bills for the time being.

Essentially this means that you won’t see any increases at the moment as the government has yet to clarify when these will be changed. On the plus side, it’s not expected until at least 2020, and will only affect cars registered after that point. Thus meaning that any car bought before then will be unaffected by WLTP changes.


How will figures vary?

As we’ve mentioned already, you can expect figures to be a more realistic indication of what you’ll get in the real-world.

While you might be used to seeing ‘urban’, ‘extra-urban’ and ‘combined’ fuel economy figures (the combined being what we use in our reviews), WLTP will see figures being listed as ‘low’, ‘medium’, ‘high’, ‘extra high’ and the ‘combined’ figure, which will be the one of importance.


Any other effects WLTP will have?

Another potential issue which could arise affects manufacturers. Many car firms have already said about the complexity of carrying out these tests, and also how time-consuming they are, which could mean that there will be less variants of new cars on sale in the short term, until more vehicle markers can get their cars ready for the tests.

Some models could also be taken off sale until they can comply with measures, while manufacturers such as Seat and Volkswagen have had to decrease the power on some cars by around 10bhp to make them comply with WLTP.


When does WLTP come into force?

While all brand new models must already meet WLTP rules, its September 1 that’s the important date, as this is when all new models on sale must have undergone the WLTP test. Some manufacturers were already ahead of the curve, with Volvo being compliant with WLTP by March 2018, while firms such as Suzuki have also been releasing its figures for WLTP for some time as well.

James Ash


Content Marketing Executive at

August 2, 2018