September marks the change to the Worldwide harmonised Light vehicle Test Procedure (WLTP)

We look at the effect this has had on the vehicle market and the challenges now faced by fleet managers


Until recently, all vehicle emissions were tested through the New European Driving Cycle (NEDC). Originally devised in 1973, the test at the time was deemed to be an unbiased comparison between car models and engine specification. Advancements in car technology now means that the test results are no longer a true reflection of modern driving behaviours.

The WLTP testing approach was introduced in September 2017 for the latest developed vehicles and those vehicles with new powertrains. From September 2018, this test structure is now applicable to ALL newly registered vehicles. During a transitional period, these vehicles will carry both WLTP and NEDC documentation but in 2020, vehicles will need to confirm to WLTP documentation only.

What are the differences between NEDC and WLTP?

In a nutshell, WLTP emission tests are much more rigorous then NEDC and provide a fairer representation of modern driving. Devised by experts under the supervision of the World Forum for Harmonization of vehicle regulations, it is deemed to be more relevant representing a tendency towards vehicles being driven more intensely and for longer durations.

The table below lists the comparisons between the tests.

- wltp / nedc -

As a more robust testing procedure, WLTP test conditions incorporate an all-round on the road performance of a vehicle. These are:

A more realistic driving behaviour
An increased range of  driving situations – motorway, main road, urban and sub-urban
Longer test conditions
Improved representation of accelerations and decelerations
Higher average and maximum speeds
Higher average and maximum driver power
Realistic ambient temperatures
Shorter stops
CO2 values and fuel consumptions are provided for individual vehicles
Stricter set up and measurement conditions
Best and worse case scenarios on customer information

WLTP is complemented by the Real Driving Emissions test (RDE2) which measures pollutants such as NOx emitted by diesel vehicles when being driven.

RDE2 ensures that realistic emission readings are delivered over all road conditions including:

Motorways (high speed)
Urban roads (low speed)
Rural roads (medium speed)
Up and downhill driving
Low and high altitudes
Additional vehicle payload
Year-round temperatures

Employees with company diesel cars registered before 1 January 1998 that are not certified to meet the RDE2 standard are subject to a diesel tax supplement of 4%. Since there are currently no diesel cars on the road that meet this standard, it is safe to say all diesel cars will incur the additional cost.

WLTP emissions results are expected to be higher than NEDC due to the more stringent test conditions. With car tax bands being dependent on vehicle emissions, the question arises – what impact will this have on fleet?

The impact of WLTP for fleet managers 

Late vehicle deliveries. Despite the transitional period, some car makers made the decision to cease or suspend production of certain models as they are aligned to WLTP standards. This resulted in late deliveries of some makes and models of cars including Volkswagen, Audi, BMW and Peugeot.

Tax implications. As vehicle excise duty is aligned with vehicle emissions, the expectation is that car taxes will increase. Don’t panic – HM Treasury has confirmed that it will not be using CO2 values from WLTP to determine tax (both VED and company car tax) from September but the future implications are still unclear.

New purchase uncertainty. Some fleets have responded to this uncertainty by extending leasing contracts. Sales of cars in the UK increased by 23% in August as car makers reduced vehicle stocks ahead of WLTP. During the same period, plug-in electric and hybrid vehicles experienced a record sales high touching almost 7,500. As a comparison, sales of the same type of vehicles in August last year were just shy of 4,000.

Diesel sales continue to decline due to the surcharge on tax due to emission output and air quality reports. Experts go as far as to predict that by 2030, sales of diesel vehicles will fall to just 5%.

What should fleet managers do now?

This is a good question! It is difficult to advise fleet managers about how they should address the changes without further clarification from the government. As mentioned previously, larger fleets have responded by extending lease periods until decisions have been made. Following government confirmation, this could mean a rush of vehicle orders that manufacturers may struggle to meet, creating order backlogs.

Having the systems in place to help reach important vehicle fuel type decisions is a good place to start. Utilise the time to gather data on your existing vehicle choices to create a checklist. include information such as:

WLTP compliance
Order availability
Expected delivery dates

Consider your CO2 parameters and where your preferred vehicles fall – sub 100g/km and sub 130g/km bandings for example. Original vehicle choices may be out of these bandings which could spell the inclusion of new vehicles and the loss of others. Such an activity can also serve as an opportunity to communicate to your drivers about vehicle choice expectations.