CO2 Calculator Ireland

CO2 Emissions and VRT Bands

Your vehicle's CO₂ emissions determine which VRT band applies, directly affecting how much tax you pay. Here's how the system works:

Current VRT Bands (WLTP)

NEDC vs WLTP - What's the Difference?

CO2 Examples by Vehicle Type

Understanding Your CO2 Impact

Where to Find CO2 Values

• Certificate of Conformity: Most reliable source with both NEDC and WLTP
• Vehicle registration documents: Usually shows official test values
• Manufacturer specifications: Check model brochures or websites
• Online databases: EU vehicle databases or manufacturer lookups

Factors Affecting CO2 Emissions

• Engine size and type: Larger engines generally produce more CO₂
• Vehicle weight: Heavier cars need more energy to move
• Aerodynamics: Sports cars vs. practical shapes
• Transmission: Manual vs. automatic efficiency differences
• Drive type: FWD, RWD, or AWD affects consumption

CO2 and Climate Impact

The VRT system is designed to encourage lower-emission vehicles:

• Financial incentive: Lower CO₂ = lower VRT
• Environmental benefit: Reduced carbon footprint
• Future-proofing: Stricter emissions standards coming
• Urban access: Some cities may restrict high-emission vehicles

CO2 Measurement Methods: NEDC vs WLTP Explained

The way vehicle CO2 emissions are measured has changed dramatically in recent years, and understanding the difference between the two main test standards is essential for accurate VRT calculation. The NEDC test was developed in the 1980s and was the standard across Europe until 2017. It was conducted under highly controlled laboratory conditions with gentle acceleration, no air conditioning running, and a fully warmed engine. The result was CO2 figures that were often 20-40% lower than what vehicles actually produced in real-world driving. A car might officially emit 110 g/km under NEDC but produce 150 g/km or more on a real Irish road with hills, traffic, and cold starts.

The WLTP test replaced NEDC from September 2017 for new type approvals and became mandatory for all new registrations from September 2018. WLTP lasts 30 minutes compared to NEDC's 20 minutes, covers four driving phases from urban stop-start to motorway speeds, starts with a cold engine, and accounts for optional equipment that affects weight and aerodynamics. WLTP CO2 figures are typically 10-25% higher than NEDC for the same vehicle, but they are notably more accurate for real-world driving. For VRT purposes, Revenue uses whichever test standard appears on your vehicle's Certificate of Conformity. If both figures are listed, Revenue generally uses the WLTP figure as the newer and more accurate standard. Always check which test standard your car was certified under before calculating your VRT.

The shift from NEDC to WLTP has had a notable financial impact on importers. A car that was rated at 115 g/km under NEDC would have been in the 14% VRT band. Under WLTP, the same car might rate at 138 g/km, moving it to the 16% band. On a vehicle worth €25,000, this difference adds €500 to the VRT bill. This is why it is essential to verify the CO2 figure on the actual documentation rather than relying on advertised figures that may quote the lower NEDC standard to make the car look cleaner and cheaper to run.

How CO2 Emissions Affect Your VRT Bill

Here's the simple version: the more CO2 your car pumps out, the more you pay in VRT. Ireland uses a banding system where your vehicle's grams per kilometre figure places it into a percentage bracket. That percentage gets applied to the Open Market Selling Price (OMSP) of your car, and that's your VRT bill.

Right now, a car emitting under 50 g/km lands in Band A at just 7%. On a car worth €25,000, that's €1,750 in VRT. Jump up to 130 g/km and you're in Band D paying 22%, which on that same €25,000 car works out to €5,500. Get yourself into the top band, anything over 190 g/km, and you're paying 41%, which is €10,250 on that same vehicle.

The jump between bands is not gradual either. Going from 119 g/km to 121 g/km, a difference of just 2 grams, can push you from one band into another with a noticeable rate increase. I've seen people lose sleep over exactly where their car falls. If you're buying a new model and the specs show 119 g/km versus 121 g/km, that tiny difference could cost you several hundred euro in extra VRT.

The system is designed this way on purpose. Revenue wants to make high-emission cars more expensive to register, nudging people toward cleaner options. Whether that actually changes buying habits or just punishes people who need bigger cars is a whole other debate.

How to Find Your Car's CO2 Emissions

The best place to look is your Certificate of Conformity (CoC). This is the official document from the manufacturer that lists every specification of your car, including both the NEDC and WLTP CO2 figures. If you're buying from a dealer, ask for it. Most will have it on file or can request it from the manufacturer.

Your vehicle registration document (the VRC in Ireland) will show the CO2 figure too, though it might only list one standard depending on when the car was registered. For cars registered after September 2018, the WLTP figure is the one Revenue uses, so make sure you're looking at the right number.

Check the manufacturer's website if you're still unsure. Most car companies publish full specs for their current and recent models, including the official CO2 readings. Toyota, for instance, lists detailed emissions data for every variant of the Corolla or Yaris, right down to the specific trim level.

One thing to watch out for: the same model with different engines or gearboxes can have wildly different CO2 figures. A Volkswagen Golf 1.0 TSI might come in at 120 g/km, while the 2.0 TDI version sits at 115 g/km. The diesel, despite being a bigger engine, often reads lower on CO2 than its petrol counterpart because diesel engines are more efficient per kilometre. The trade-off is higher NOx emissions, which is a separate tax entirely.

Online databases like the EU's vehicle type approval records can also help, especially for imports. If you're bringing in a car from the UK or Europe and need to confirm its emissions data, these databases are free to search and usually up to date.

CO2 Emissions by Fuel Type

Fuel type matters a lot when it comes to CO2. Here's roughly what you're looking at for each category, based on typical figures from current models.

Petrol cars usually sit between 100 and 180 g/km for standard hatchbacks and saloons. A small car like a Hyundai i20 might come in around 110 g/km, while a bigger petrol engine like the 2.0-litre in a Mazda 6 pushes closer to 150 g/km. Direct injection and turbocharging have helped bring petrol figures down over the last few years, but they still tend to read higher than equivalent diesels on the CO2 front.

Diesel engines generally produce less CO2 per kilometre than petrol, typically 20 to 40 g/km less for comparable power output. That's why you'll see a 1.6-litre diesel hatchback sitting at 95 g/km while the petrol version of the same car comes in at 125 g/km. The diesel advantage on CO2 has been a big selling point for years, though the dieselgate fallout and rising NOx taxes have dented that somewhat.

Hybrids split the difference depending on the type. A standard petrol hybrid like the Toyota Corolla Hybrid might manage 90 to 100 g/km in mixed driving. Plug-in hybrids can technically hit very low figures, sometimes under 30 g/km, but only if you actually charge them regularly and do most of your driving on electric power. Run a plug-in hybrid mostly on petrol and the real-world CO2 climbs back up toward 120 g/km or higher.

Electric vehicles sit at 0 g/km on paper, which puts them in the lowest VRT band. There are caveats there around how the battery is manufactured and where your electricity comes from, but for VRT purposes, zero is zero.

CO2 Emissions by Car Model

Looking at real models helps put the numbers in perspective. Here are some examples from cars you'll actually see on Irish roads.

The Toyota Yaris Hybrid sits around 92 g/km WLTP, putting it in the 81 to 120 bracket with a VRT rate of about 14%. A Ford Fiesta 1.0 EcoBoost petrol comes in around 113 g/km, landing in the same band. Both small, both economical, but the Fiesta petrol just edges into the next rate if you pick a different spec.

Move up to family cars and the numbers shift. The Hyundai Tucson 1.6 T-GDi petrol hybrid sits around 140 g/km, while the diesel version of the same car comes in at roughly 125 g/km. That difference puts the petrol version into Band D at 22% VRT versus the diesel in Band C at around 18%. On a car valued at €35,000, that's roughly €1,400 extra in VRT for choosing petrol over diesel.

SUVs and larger vehicles tend to sit in the higher bands. A BMW X5 xDrive30d, a popular enough car in Ireland, comes in at around 175 g/km, putting it in the 151 to 190 bracket at 32% VRT. Add the NOx charge on top of that and registering a car like that is not cheap. The fully electric BMW iX, by comparison, hits 0 g/km and qualifies for the lowest rate.

Performance cars are a different world entirely. Something like a Mercedes-AMG C63, with its 4-litre V8, can push past 230 g/km. That puts you in the top band at 41% with a minimum VRT of €820. You're paying premium prices for the car and then getting hit with the maximum VRT rate on top.

How to Reduce Your CO2-Based VRT

The most straightforward way to pay less VRT is to pick a car with lower CO2. It sounds obvious, but there are practical ways to do it without settling for something you don't want.

If you're set on a particular model, check which engine variant has the lowest emissions. Car manufacturers often offer multiple engines for the same model, and the differences in CO2 can be substantial. A 1.0-litre three-cylinder petrol might emit 30 g/km less than the 1.5-litre four-cylinder in the same range. The smaller engine might feel less powerful, but for city driving it makes little difference day to day.

Consider a hybrid version of a car you already like. Many manufacturers now offer hybrid options across their lineup. A plug-in hybrid of the same model might save you thousands in VRT compared to the pure petrol or diesel version, especially if your daily commute is short enough to run mostly on electric power.

Transmission choice affects CO2 too. In some models, the automatic gearbox is more efficient than the manual, which seems counterintuitive. Dual-clutch automatics in particular can bring the figure down by 5 to 10 g/km compared to the manual option.

For used imports, pay attention to the spec. Larger alloy wheels, panoramic sunroofs, and four-wheel drive all add weight or drag, which pushes CO2 up. The base model of a car often has the lowest emissions in the range. It's worth comparing the exact variant you're looking at rather than assuming all versions of a model have similar figures.

If you're importing from the UK, remember that post-Brexit, UK-registered cars still follow the same CO2 standards. The WLTP figure on a UK spec sheet is the same one Revenue will use, so there's no conversion needed. What does change is the exchange rate, which affects the OMSP calculation, but that's a separate factor from your CO2 band.