NEDC vs WLTP: What Irish Car Importers Need to Know in 2026

What Is NEDC?

NEDC stands for New European Driving Cycle. It was the emissions testing standard used across Europe from 1992 until the late 2010s. The test was designed to measure exhaust emissions and fuel consumption under laboratory conditions using a rolling road dynamometer.

The test itself is straightforward. It runs for roughly 20 minutes, covers about 11 km, and has two phases: an urban cycle with repeated starts, stops, and idling, followed by an extra-urban cycle that pushes the speed up to 120 km/h. The average speed works out to about 33.6 km/h.

For decades, NEDC was the only game in town. But by the 2010s, it was widely criticised. Real-world fuel consumption and CO2 emissions routinely came in 20-40% higher than the official NEDC numbers suggested. The test was too gentle. There were no hills, no wind resistance, no air conditioning running, no aggressive overtaking. Manufacturers learned to optimise their engines specifically for the test cycle — a practice that made the numbers look good on paper without reflecting how people actually drive.

For Irish VRT purposes, NEDC matters because millions of cars still carry NEDC CO2 figures on their documentation. Any car first registered before September 2018 will almost certainly have an NEDC rating. Revenue Ireland accepts these figures for VRT, so understanding what they represent — and how they compare to WLTP — is essential when importing a used car.

What Is WLTP?

WLTP stands for Worldwide Harmonised Light Vehicle Test Procedure. It was developed by the United Nations as a replacement for NEDC, designed to produce more realistic and globally consistent emissions data. The EU mandated WLTP for all new type approvals from September 2017, and for all new vehicle registrations from September 2018. Ireland adopted this timeline.

The test is considerably more demanding than NEDC. It lasts approximately 30 minutes (50% longer), covers 23.3 km (more than double NEDC's 11 km), and is divided into four phases: low speed, medium speed, high speed, and extra-high speed. Vehicles reach a maximum speed of 131 km/h during the extra-high phase. The average speed is 46.5 km/h compared to NEDC's 33.6 km/h.

Unlike NEDC, the WLTP test includes cold starts. It uses more dynamic acceleration and deceleration profiles. It accounts for optional equipment — things like alloy wheels, roof rails, and larger spoilers that change a car's weight and aerodynamics. Two variants of the same model can end up with different WLTP CO2 figures depending on their specification.

The result? WLTP CO2 figures are generally 10-25% higher than NEDC numbers for the same vehicle. That does not mean the car pollutes more under WLTP — it means the test measures it more honestly. WLTP values are much closer to real-world driving emissions, which makes them a fairer basis for taxation, even if the higher numbers sometimes come as an unwelcome surprise.

Key Differences Between NEDC and WLTP

The table below lays out the technical differences side by side. If you are importing a car and trying to figure out whether you are looking at an NEDC or WLTP figure, these numbers help explain why they do not match.

The practical takeaway is this: if you have two versions of the same car, one rated NEDC and one rated WLTP, the WLTP figure will always be higher. That does not make the car dirtier — it makes the measurement more honest.

How This Affects Your VRT

Vehicle Registration Tax in Ireland is calculated primarily on your car's CO2 emissions measured in grams per kilometre (g/km). That CO2 figure drops your car into a specific VRT band, and that band determines the percentage rate applied to the vehicle's open market selling price (OMSP). The current VRT bands for the 20-band WLTP system range from 7% (for cars at or below 50 g/km) up to 41% (for cars above 191 g/km).

Here is the core problem: the same car gets a different CO2 number depending on whether it was tested under NEDC or WLTP. Because WLTP figures run 10-25% higher, the car often lands in a higher VRT band. That means more tax — sometimes a lot more.

Revenue Ireland does not give you a choice. You must use the figure on your vehicle's Certificate of Conformity. If the car was type-approved under NEDC, you use the NEDC number. If it was type-approved under WLTP, you use the WLTP number. During the transition period (September 2017 to August 2018), some cars carry both figures, and Revenue uses the WLTP figure when one is available.

Worked Examples: NEDC vs WLTP in Real Money

Numbers talk. Here are two concrete examples showing how the same car can land in different VRT bands depending on which test cycle produced its CO2 figure. We have used the 20-band WLTP VRT rates that apply in Ireland from 2024 onward.

Current 20-Band WLTP VRT Rates

Since Ireland adopted the 20-band WLTP system, these are the CO2-to-rate thresholds that apply. Revenue uses whichever test cycle produced your car's declared figure. Check the full VRT bands page for the latest updates.

Other VRT Factors to Watch

The NEDC vs WLTP difference is not the only variable that affects your final VRT bill. A few other points worth knowing:

NOx Levy: For diesel cars, the NOx levy adds on top of the VRT band rate. Cars emitting ≤60 mg/km of NOx pay €5. Those between 61-80 mg/km pay €300 plus €15 per mg/km over 60. Cars above 80 mg/km pay €600 plus €25 per mg/km over 60, capped at €4,850 for diesel and €600 for petrol. The test cycle used for NOx also follows the type-approval standard.

Electric Vehicle Relief: Battery electric vehicles qualify for up to €5,000 off VRT. This tapers to €0 once the OMSP reaches €50,000. The relief has been extended to 31 December 2026. Since EVs produce zero tailpipe CO2, they fall into the lowest VRT band at 7% before the relief is applied.

PHEV Relief: The plug-in hybrid VRT relief ended on 31 December 2021. PHEVs now pay full VRT based on their WLTP CO2 figure. If you are importing a PHEV, check the official WLTP number — some models saw their CO2 figures rise significantly under WLTP compared to the older NEDC-based claims.

Use our emissions calculator to see exactly what you will pay based on your car's specific CO2 figure, fuel type, and OMSP.

Can I Choose Which Cycle to Use?

No. Revenue does not let you pick the more favourable test cycle. You must use whichever figure appears on the vehicle's Certificate of Conformity or registration document. If the car was type-approved under NEDC, you declare the NEDC number. If it was type-approved under WLTP, you declare the WLTP number.

This comes up most often during the transition period from September 2017 to August 2018, when some vehicles carry both NEDC and WLTP ratings on the same document. In those cases, Revenue uses the WLTP figure if one is available, because it is the more recent and more accurate standard. You cannot opt for the lower NEDC figure to save on tax.

If you are buying from a dealer, ask them to confirm which test cycle the car was type-approved under before you agree a price. If you are importing privately, check the V5C logbook for UK vehicles or the Certificate of Conformity for EU vehicles. The information is there — but you have to look for it.

Which Test Cycle Applies to Your Car?

It depends entirely on when the car was first registered. Here is a quick guide:

For UK imports, the same timeline applies. Cars registered in the UK before September 2018 almost always carry NEDC figures. Cars registered from September 2018 onward carry WLTP figures. If you are importing a 2019 or newer car, you are firmly in WLTP territory and there is no conversion to worry about.

If you are importing a car from the 2017-2018 window, check the documentation carefully. Some sellers will advertise the lower NEDC figure because it looks better, but Revenue may use the WLTP figure for VRT. Always verify before committing to a purchase.

Frequently Asked Questions