NEDC vs WLTP Guide Ireland
Understand how emissions testing affects your VRT. Convert between NEDC and WLTP, find your car's CO2 band, and calculate accurate Vehicle Registration Tax.
Convert NEDC to WLTPWhat Is NEDC?
NEDC stands for New European Driving Cycle. It was the emissions testing standard used across Europe from 1992 until 2017. The test was designed to measure car exhaust emissions and fuel consumption under controlled laboratory conditions.
The NEDC test lasts roughly 20 minutes and includes two main parts: an urban cycle with repeated acceleration, deceleration, and idling, followed by an extra-urban cycle representing higher-speed driving. The maximum speed reached during the test is 120 km/h, and the average speed is about 33.6 km/h.
While NEDC was the standard for over two decades, it was widely criticised for being unrealistic. The test took place on a rolling road with no wind, no hills, no air conditioning, and no variation in driving style. As a result, real-world fuel consumption and CO2 emissions were often 20-40% higher than the official NEDC figures suggested.
For Irish VRT purposes, vehicles type-approved under NEDC carry CO2 values that are typically lower than what the same car would achieve under the newer WLTP test. This is important because your CO2 figure directly determines which VRT band your vehicle falls into.
What Is WLTP?
WLTP stands for Worldwide Harmonised Light Vehicle Test Procedure. It replaced NEDC as the official emissions testing standard in the EU from September 2017 for new type approvals, and September 2018 for all new vehicle registrations. Ireland adopted this timeline.
WLTP was developed by the United Nations to create a more realistic and globally consistent test. The procedure lasts approximately 30 minutes and is divided into four phases: low speed (urban), medium speed (suburban), high speed (rural road), and extra-high speed (motorway). Vehicles reach speeds of up to 131 km/h during the test.
Unlike NEDC, the WLTP test includes more dynamic driving with higher acceleration rates, a wider range of driving conditions, and a cold start component. It also accounts for optional equipment that affects weight and aerodynamics, meaning two variants of the same car model can have different WLTP CO2 figures.
Because of these differences, WLTP CO2 results are generally 10-25% higher than NEDC figures for the same vehicle. This shift is why many cars moved into higher VRT bands when Ireland transitioned to WLTP. However, WLTP values are much closer to real-world driving emissions, making them a fairer basis for taxation.
NEDC vs WLTP: Key Differences
| Feature | NEDC | WLTP |
|---|---|---|
| Full Name | New European Driving Cycle | Worldwide Harmonised Light Vehicle Test Procedure |
| Test Duration | 20 minutes | 30 minutes |
| Test Phases | 2 phases (urban + extra-urban) | 4 phases (low, medium, high, extra-high) |
| Maximum Speed | 120 km/h | 131 km/h |
| Average Speed | 33.6 km/h | 46.5 km/h |
| Distance Covered | 11 km | 23.3 km |
| Cold Start | No (warm start only) | Yes (includes cold start) |
| Driving Dynamics | Gentle accelerations, constant speeds | Dynamic accelerations, variable speeds |
| Optional Equipment | Not accounted for | Tested with standard and optional equipment |
| Vehicle Variants | One test per vehicle family | Each variant tested individually |
| Real-World Accuracy | 20-40% optimistic | 10-20% optimistic |
| Used In Ireland Since | 1992 | September 2017 (type approval), September 2018 (all registrations) |
Why Does It Matter for VRT?
Vehicle Registration Tax (VRT) in Ireland is calculated primarily based on a car's CO2 emissions measured in grams per kilometre (g/km). The CO2 figure you declare determines which VRT band your vehicle falls into, and therefore what percentage rate is applied to the vehicle's open market selling price (OMSP).
Because WLTP CO2 values are typically 10-25% higher than NEDC values for the same car, the test cycle your vehicle was type-approved under has a direct financial impact. A car tested under NEDC at 110 g/km sits in the 14% VRT band. The same car under WLTP might register at 130 g/km, pushing it into the 16% band. For a vehicle with an OMSP of EUR 25,000, that difference represents an extra EUR 500 in VRT.
Revenue Ireland uses whichever emissions figure appears on the vehicle's Certificate of Conformity or registration document. You cannot choose the more favourable test standard. This is why it is essential to check your vehicle's documentation carefully before calculating VRT.
Practical Tip
Always verify whether your car was type-approved under NEDC or WLTP. Check the Certificate of Conformity, the V5C logbook for UK imports, or the NCTS registration document. Using the wrong figure can result in an inaccurate VRT estimate and a surprise bill at registration.
NEDC to WLTP Conversion
There is no official, universal conversion factor between NEDC and WLTP because the difference depends on the specific vehicle, engine type, weight, and aerodynamics. However, research by the European Commission and independent testing organisations has identified typical ranges for common vehicle categories.
Use the following table as a general guide. For your exact VRT calculation, always use the WLTP figure printed on the vehicle's Certificate of Conformity.
| NEDC CO2 (g/km) | Approx. WLTP CO2 (g/km) | Typical Increase | VRT Band Change |
|---|---|---|---|
| 90 | 105 - 110 | +15-22% | 14% band (stays same) |
| 110 | 128 - 135 | +16-23% | 14% moves to 16% |
| 130 | 150 - 160 | +15-23% | 16% moves to 20% |
| 150 | 172 - 185 | +15-23% | 20% moves to 24% |
| 170 | 195 - 210 | +15-24% | 24% moves to 28% |
| 190 | 218 - 235 | +15-24% | 28% moves to 32% |
| 210 | 240 - 260 | +14-24% | 32% stays same or 36% |
Conversion Calculator
Enter your NEDC CO2 value below to get an estimated WLTP equivalent. Remember, this is an approximation. Your actual WLTP figure may vary.
How to Find Your Car's Test Cycle
Knowing whether your vehicle was tested under NEDC or WLTP is essential for accurate VRT calculation. Here is where to find this information:
- Certificate of Conformity (CoC): This is the primary document issued by the vehicle manufacturer. It states whether the emissions were measured under NEDC or WLTP, and lists the exact CO2 figure. All EU-imported vehicles should come with a CoC.
- V5C Registration Certificate (UK imports): For vehicles imported from the UK, the V5C logbook shows the "official fuel consumption" and emissions data. UK vehicles registered before September 2018 typically show NEDC figures. After that date, WLTP is standard.
- NCTS Registration Documents: When you register a vehicle at an NCTS centre in Ireland, the CO2 value on file determines your VRT band. Check this figure before finalising your VRT calculation.
- Manufacturer's Website: Most car manufacturers list technical specifications including the test standard on their official websites. Search for your exact model variant to find the CO2 data.
- Vehicle Logbook / Owner's Manual: Some vehicles include emissions data in the owner's manual or a separate technical data sheet.
Tip for UK Imports
If you are importing a car from the UK registered between 2017 and 2018, it may have dual NEDC and WLTP ratings. Revenue Ireland will accept either figure. However, it is worth checking which one applies to your specific variant, as using the WLTP figure may result in a higher VRT band.
Impact on VRT Band: Worked Examples
Understanding how the test cycle affects your VRT band is the key to avoiding surprises. Below are worked examples showing the real cost difference between NEDC and WLTP for the same vehicle.
Example 1: 2017 Volkswagen Golf 1.6 TDI
NEDC CO2: 99 g/km — falls in the 14% VRT band
WLTP CO2: 118 g/km — falls in the 16% VRT band
OMSP: EUR 18,000
NEDC VRT: EUR 18,000 x 14% = EUR 2,520
WLTP VRT: EUR 18,000 x 16% = EUR 2,880
Difference: EUR 360 more under WLTP
Example 2: 2019 BMW 320d
NEDC CO2: 115 g/km — 16% VRT band
WLTP CO2: 138 g/km — 16% VRT band
OMSP: EUR 35,000
NEDC VRT: EUR 35,000 x 16% = EUR 5,600
WLTP VRT: EUR 35,000 x 16% = EUR 5,600
Difference: Same band, same VRT in this case
Example 3: 2020 Toyota Corolla Hybrid
NEDC CO2: 79 g/km — 7% VRT band (PHEV/hybrid rate)
WLTP CO2: 104 g/km — 14% VRT band
OMSP: EUR 22,000
NEDC VRT: EUR 22,000 x 7% = EUR 1,540
WLTP VRT: EUR 22,000 x 14% = EUR 3,080
Difference: EUR 1,540 more under WLTP — a notable jump across bands
These examples show that the financial impact of the NEDC-to-WLTP shift varies. Some vehicles stay in the same band, while others move up one or more bands, resulting in hundreds or even thousands of euros in additional VRT.
Which Cars Are Affected?
The transition from NEDC to WLTP happened in phases. Here is the timeline that determines which test standard applies to your vehicle:
| Period | Test Standard | Impact |
|---|---|---|
| 1992 - 2017 | NEDC only | All vehicles registered in Ireland during this period used NEDC CO2 figures. |
| September 2017 - August 2018 | Transition period | New type approvals required WLTP. Some vehicles carry dual NEDC and WLTP ratings. |
| September 2018 onwards | WLTP mandatory | All new registrations in Ireland must use WLTP CO2 figures. |
The vehicles most affected are those registered between 2017 and 2019, where dual ratings exist. For UK imports, pre-September 2018 vehicles almost always carry NEDC figures. Post-September 2018 imports carry WLTP.
If you are importing a newer vehicle (2019 onwards), it will already have WLTP CO2 values. The conversion is only relevant when comparing across the two standards or when a vehicle has been type-approved under both.
Why NEDC Still Matters for VRT in 2026
Even though WLTP became mandatory for new registrations in September 2018, NEDC remains deeply relevant for anyone importing a used car into Ireland. Millions of cars on Irish roads were type-approved under NEDC, and every used car imported from the UK or EU that was first registered before 2019 will carry NEDC CO2 figures on its documentation. Revenue Ireland still accepts these figures for VRT calculation purposes, provided they appear on the vehicle's Certificate of Conformity or registration document.
Understanding NEDC is also essential for accurate price comparisons. If you are looking at two similar cars and one has NEDC CO2 figures while the other has WLTP, you cannot directly compare their CO2 numbers. The NEDC figure will always be lower, but that does not mean the car is cleaner. A car with 110 g/km NEDC might be equivalent to a 135 g/km WLTP car in real-world terms. Using the wrong standard for comparison could lead you to overpay for a vehicle that looks efficient on paper but actually emits much more in real driving.
Many online listings for used imports still advertise the NEDC figure because it is lower and more attractive to buyers. If you are serious about calculating your VRT accurately, always look for the WLTP figure on the actual documentation. Our conversion calculator above provides an estimate, but the official figure on the Certificate of Conformity is what Revenue will use. Do not rely on what the seller advertises or what an online listing says, because the wrong figure can shift your VRT by hundreds or thousands of euro.
NEDC vs WLTP FAQs
What is the difference between NEDC and WLTP?
NEDC (New European Driving Cycle) was the older emissions test used in Europe from 1992 until 2017, running for 20 minutes with a maximum speed of 120 km/h under highly controlled laboratory conditions. WLTP (Worldwide Harmonised Light Vehicle Test Procedure) replaced it, lasting 30 minutes with speeds up to 131 km/h, including more dynamic driving patterns, cold starts, and a wider range of conditions. WLTP CO2 figures are typically 10-25% higher than NEDC for the same vehicle, but they are much closer to real-world driving emissions. The shift from NEDC to WLTP was driven by the need for more accurate, transparent, and realistic emissions testing after years of criticism that NEDC figures bore little resemblance to actual road performance.
Does my car use NEDC or WLTP for VRT in Ireland?
Ireland uses the emissions test standard that was current when your car was type-approved by the manufacturer. Cars registered before September 2018 in the EU typically carry NEDC figures on their documentation. Cars registered from September 2018 onwards generally use WLTP. Revenue Ireland accepts whichever figure appears on your vehicle's Certificate of Conformity or vehicle registration document. You cannot choose the more favourable standard. During the transition period from September 2017 to August 2018, some vehicles carry both NEDC and WLTP ratings. In these cases, Revenue will typically use the WLTP figure if one is available, as it is the newer and more accurate standard.
How do I convert NEDC CO2 to WLTP CO2?
There is no official single conversion factor because the difference varies notably by vehicle type, engine technology, weight, and aerodynamics. A common approximation is to multiply the NEDC value by 1.15 to 1.25 to estimate the WLTP equivalent. For example, an NEDC figure of 100 g/km would be approximately 115-125 g/km under WLTP. The European Commission has published correlation tables that provide more precise conversion factors for specific vehicle categories, but these are guidance only. For accurate VRT calculation, always use the official WLTP figure printed on the vehicle's Certificate of Conformity rather than a converted estimate. Our conversion calculator above provides a useful approximation for budgeting purposes.
Which VRT bands apply for NEDC vs WLTP?
The VRT band thresholds are the same regardless of which test standard is used, but the CO2 value that determines your band placement will differ. Under NEDC, a petrol car with 110 g/km CO2 falls in the 14% VRT band. Under WLTP, that same car might have 130 g/km, placing it in the 16% band. The Irish VRT band system uses fixed CO2 thresholds, and your car's declared figure places it into whichever bracket applies. Revenue applies the correct band based on the test cycle recorded for your vehicle's documentation. It is essential to check whether your car's figure is NEDC or WLTP before using the VRT band table, because the wrong assumption could lead to an inaccurate estimate that is hundreds or thousands of euro off.
Will I pay more VRT under WLTP than NEDC?
Yes, in most cases you will pay more VRT under WLTP. Because WLTP CO2 figures are typically 10-25% higher than NEDC for the same vehicle, the car often falls into a higher VRT band. For example, a car with 119 g/km NEDC would be in the 14% VRT band, but if its WLTP figure is 140 g/km, it moves to the 16% band. On a vehicle with an OMSP of €25,000, this difference adds €500 in VRT. For higher-value vehicles or those that jump multiple bands, the additional cost can be €2,000 or more. The practical implication is that a used car that looks cheap based on its NEDC rating may be notably more expensive to register than expected once the WLTP figure is applied.
When did Ireland switch from NEDC to WLTP?
The EU mandated WLTP for all new type approvals from September 2017, and for all new vehicle registrations from September 2018. Ireland followed this EU timeline without deviation. Vehicles registered before September 2018 typically have NEDC test results on their documentation. From September 2018 onward, WLTP became the required standard for all new registrations in Ireland. For vehicles imported from the UK, the same timeline applies because the UK adopted WLTP under EU regulations before Brexit. Understanding this timeline helps you quickly identify which test standard your vehicle should carry based on its first registration date.
Can I choose which test cycle to use for VRT?
No. You must use the test cycle that appears on your vehicle's Certificate of Conformity or registration document. Revenue does not allow you to choose the more favourable standard between NEDC and WLTP. If your car was type-approved under WLTP, you must declare the WLTP CO2 figure for VRT purposes, even if an NEDC figure also exists for the same vehicle. This is a common trap for buyers looking at cars from the 2017-2019 transition period, where both figures may be listed. Some sellers will advertise the lower NEDC figure to make the car look more attractive, but Revenue will use the WLTP figure if available. Always check the documentation yourself rather than relying on advertised figures.
Does NEDC still affect any other taxes or charges in Ireland?
Yes, NEDC figures are still used for motor tax calculation on many older vehicles. Ireland's motor tax system uses a different set of CO2 bands that still reference NEDC figures for cars registered before 2021. If you import a used car with an NEDC CO2 figure, the motor tax you pay annually will be calculated based on that figure using the motor tax CO2 band system, which operates separately from VRT bands. The annual motor tax for a car with 100 g/km NEDC might be around €180, while the same car rated at 130 g/km WLTP might fall into a higher motor tax band. This dual-system approach means that the difference between NEDC and WLTP can affect both your upfront VRT cost and your ongoing annual motor tax.