What is WLTP?

The Worldwide Harmonised Light Vehicle Test Procedure or WLTP, for short, is a vehicle fuel economy test that you might have come across when reading about new electric vehicles – but what is it?

What is WLTP?

On September 1st 2018, WLTP became mandatory for measuring the C02 emissions and EV ranges on all new cars in the EU. WLTP replaced the old NEDC (New European Driving Cycle) testing that had been used since the 1980s.


What does the test involve?

Testing begins under laboratory conditions on a rolling road. The procedure itself takes about 30 minutes but all the processes after can continue for up to five days.

One test is completed at 23°C and another is done at 14°C to more fairly reflect real world conditions and European temperatures.

In comparison with the old NEDC standard, WLTP uses a greater range of driving cycles and uses sharper acceleration and deceleration. Vehicles will travel at a higher average speed and higher maximum speed too.

After tests in the laboratory are finished, Real Driving Emissions (RDE) testing takes place. RDE testing can take up to 2 hours and usually the vehicle will cover over 50 miles on a combination of rural, urban and motorway routes. This real world driving helps give more validity to the initial WLTP testing.

A Portable Emissions Measurement System (PEMS) is fixed to the car’s exhaust during the testing to measure pollutants whilst driving, which must be below specific limits.

Many studies have shown that WLTP testing is much nearer to real-world true MPG test data than the previous NEDC system.


Why does WLTP matter?

Pollution used to be no more than an afterthought for big car manufacturers when they've built cars in years gone by, but now with the growing concerns over climate change, car manufacturers are being pressured into making cleaner and greener vehicles.

New legislation in recent years has caused more polluting vehicles to be hit harder with road tax bills, with further fines being issued when such vehicles enter clean air zones.

WLTP was invented to more precisely measure a vehicle’s emission levels in a world that is becoming more concerned about pollution and the environment.

On top of this, WLTP enables big car manufacturers to be more transparent with its customers, which also allows consumers to make more informed buying decisions.

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