What does WLTP mean and how did this test emerge

WLTP or Worldwide Harmonized Light Vehicle Test Procedure is a testing procedure applied to all vehicles for fuel consumption, whether it's fossil fuel or electricity, as well as for CO2 emissions, applied since 2018. Thus, WLTP became a replacing testing procedure for NEDC or New European Driving Cycle, a procedure which was used since the 90s to evaluate the aforementioned performances in Europe.

The WLTP testing standard was developed from the very beginning to implement a solution for the precise evaluation of the fuel consumption, as well as the emissions, of a vehicle for the urban, extra-urban, highway, as well as mixed usage. Depending on a vehicle's year of manufacturing, more WLTP results are included, such as average consumption and emission values, as well as minimum and maximum results.

The WLTP testing procedure was made based on multiple driving styles, through data collected from Europe, Asia and the US. Each car is tested in lab-controlled conditions, which simulate outside driving conditions, from temperature and speed, and include accelerations or brake tests, as well.

What are the factors evaluated in a vehicle's WLTP testing

Firstly, there are 4 representative phases for the fuel consumption and the emissions of a vehicle, low, medium, high and very high, depending on a driver's driving style.

The specialized personnel that evaluate the vehicles conduct multiple tests, such as braking, acceleration or stopping, to offer a comprehensive perspective on a car's behavior in different driving scenarios. Thus, drivers that adopt a sporty driving style have access to numbers that accurately reflect the way they operate their vehicles and same goes for those that drive their cars in a slower, more relaxed way.

According to BYD, this is how WLTP testing is being done:

  • cycle duration: 30 minutes
  • cycle distance: 23.25 km
  • driving phases: 52% urban, 48% non-urban
  • average speed: 46.5 kph
  • maximum speed: 131 kph
  • gear shifts: vehicle-dependent shift points
  • influence of optional equipment: considered

For hybrid and electric cars an additional test is also considered, which involved testing the vehicles in a scenario that is urban-exclusive, for pure electric driving at lower speeds.

WLTP vs NEDC

To better illustrate the differences between the two testing standards and the emissions and fuel consumption performances, we will quote some data from BMW:

  • the testing time-frame increased from 20 to 30 minutes
  • cold-start temperature for the cars is currently set at 14 degrees Celsius, compared to 20-30 degrees Celsius that it was in the past
  • total driven distance increased to 23 kilometers from 11 kilometers
  • stationary time proportion of the whole test dropped from 25% to 13% currently
  • the maximum speed limit increased from 120 kph to 131 kph
  • the average speed limit is 46.5 kph compared to 34 kph that was in the past

As far as the differences between the results are concerned, some reports indicate that vehicles registered higher emissions per kilometer by 9.6 grams on the WLTP standard compared to NEDC, while the range was overestimated by just 10% in WLTP, compared to 25-30% for NEDC.

How WLTP tests can help you pick the right car

For some drivers, emissions and fuel consumption are among the main pillars when they pick a particular model, whether it's electric, hybrid, petrol or diesel. The fact that the WLTP procedure offers more accurate data, obtained in testing environments that closely resemble real-world driving conditions, can only be a good thing for drivers, as now you won't see astronomical differences between manufacturer results and your own.

Sure, you can still get a car to use significantly more fuel, by driving very aggressively or if you are waiting in the parking lot with your engine turned on for more than 2 minutes. The idea behind WLTP tests is to offer a more accurate and precise evaluation of a vehicle's fuel economy and CO2 emissions performance, while taking multiple scenarios into account.

It's not necessarily a perfect standard and we may never develop one such procedure, given that each driver uses their car differently, but by continuously updating testing procedures, we will be able to better estimate how much fuel a car consumes and very importantly, how much it pollutes the atmosphere.