Checking your car’s CO2 emissions in the UK is easier than you think. You can find this information through your V5C registration document, online DVLA services, or the vehicle manufacturer’s specifications. This data affects your road tax, company car tax, and helps you understand your vehicle’s environmental impact.
Why Car CO2 Emissions Matter in the UK
CO2 emissions directly impact your wallet and the environment. The UK government uses these figures to calculate Vehicle Excise Duty (road tax), with higher-emission cars paying significantly more.
For company car drivers, CO2 emissions determine your Benefit-in-Kind tax rate. A car emitting 50g/km of CO2 faces a 12% tax rate, whilst one emitting 170g/km faces 37%.
The UK aims for net-zero emissions by 2050. Understanding your car’s CO2 output helps you make informed decisions about upgrades or alternatives.
How to Check CO2 Emissions Using Your V5C Document
Your V5C registration certificate contains your vehicle’s official CO2 emissions figure. Look for section “49” on newer V5C documents or section “F.2” on older versions.
Step-by-step process:
- Locate your V5C document (also called the log book)
- Find section 49 or F.2 depending on your document version
- The figure shows grams of CO2 per kilometre (g/km)
- This is your vehicle’s official WLTP (Worldwide Harmonised Light Vehicle Test Procedure) rating
If you’ve lost your V5C, you can apply for a replacement through DVLA for £25.
Using DVLA Online Services to Check CO2 Emissions
The DVLA’s online vehicle enquiry service provides instant access to your car’s CO2 emissions data.
What you need:
- Vehicle registration number
- Make of the vehicle
How to access:
- Visit the DVLA vehicle enquiry service
- Enter your registration number
- Select your vehicle make from the dropdown
- View the CO2 emissions figure in the results
This free service works 24/7 and provides the same official data found on your V5C document.
Finding CO2 Emissions Through Manufacturer Specifications
Vehicle manufacturers publish detailed specifications including CO2 emissions for all their models. This method works particularly well for newer vehicles or when researching potential purchases.
Major UK manufacturer resources:
- Ford: Technical specifications section on model pages
- Vauxhall: Environmental data in vehicle brochures
- BMW: Efficiency details under technical data
- Volkswagen: Emissions data in model specifications
Search for your exact model, engine size, and transmission type. CO2 figures can vary significantly between different versions of the same car.
Understanding Different CO2 Testing Standards
The UK uses specific testing procedures to measure CO2 emissions. Understanding these helps you interpret the figures correctly.
WLTP vs NEDC Standards
WLTP (Worldwide Harmonised Light Vehicle Test Procedure):
- Current standard for all new cars
- More realistic driving conditions
- Higher CO2 figures than old NEDC tests
- Mandatory since September 2019
NEDC (New European Driving Cycle):
- Older testing standard
- Often showed lower, less realistic figures
- Still referenced for some older vehicles
- Being phased out completely
| Testing Standard | Real-world Accuracy | Usage Period |
|---|---|---|
| WLTP | High – reflects actual driving | 2019 onwards |
| NEDC | Low – laboratory conditions | Pre-2019 |
Real Driving Emissions (RDE)
RDE testing measures emissions during actual road driving. This complements WLTP laboratory tests and ensures cars meet standards in real-world conditions.
CO2 Emissions and UK Road Tax Bands
Your car’s CO2 emissions determine which Vehicle Excise Duty band you fall into. These bands have changed several times, affecting cars registered in different years.
Current Tax Bands (Cars Registered After April 2017)
| CO2 Emissions (g/km) | First Year Rate | Standard Rate |
|---|---|---|
| 0 | £0 | £0 |
| 1-50 | £10 | £165 |
| 51-75 | £25 | £165 |
| 76-90 | £115 | £165 |
| 91-100 | £140 | £165 |
| 101-110 | £160 | £165 |
| 111-130 | £180 | £165 |
| 131-150 | £220 | £165 |
| 151-170 | £555 | £165 |
| 171-190 | £895 | £165 |
| 191-225 | £1,345 | £165 |
| 226-255 | £1,910 | £165 |
| Over 255 | £2,245 | £165 |
Cars with a list price over £40,000 pay an additional £335 yearly for five years.
Legacy Tax Bands (Cars Registered Before April 2017)
Older vehicles follow different bands based on their registration date. Cars registered between March 2001 and April 2017 use CO2-based bands ranging from £0 to £580 annually.
Using Online CO2 Emissions Databases
Several online databases provide comprehensive CO2 emissions data for UK vehicles.
Vehicle Certification Agency (VCA) Database
The VCA database contains official fuel consumption and CO2 emissions data for all cars sold in the UK.
Search features:
- Make and model lookup
- Fuel type filtering
- Transmission type selection
- CO2 emissions comparison
Parkers Car Guide
Parkers provides user-friendly CO2 emissions data alongside other vehicle specifications. Their database covers both current and historical models.
What Car? Specifications
What Car? magazine’s website includes detailed CO2 emissions data for most vehicles, often with real-world testing results alongside official figures.
How to Check CO2 Emissions When Buying a Used Car
Before purchasing a used vehicle, always verify its CO2 emissions independently. This affects your ongoing costs and helps avoid surprises.
Pre-purchase checks:
- HPI Check: Include CO2 emissions verification in your vehicle history check
- Insurance Group: Higher CO2 emissions often correlate with higher insurance groups
- Service History: Well-maintained engines typically meet their stated emissions figures
- MOT History: Check for emissions-related failures through MOT history service
Red flags to watch:
- Missing or damaged catalytic converters
- Engine management warning lights
- Unusual exhaust smoke or smells
- Aftermarket modifications affecting emissions systems
MOT Test and CO2 Emissions Monitoring
The MOT test includes emissions testing, though it focuses on harmful pollutants rather than CO2 specifically.
What MOT Tests Measure
Petrol cars:
- Carbon monoxide (CO) levels
- Hydrocarbon (HC) emissions
- Lambda reading (oxygen sensor efficiency)
Diesel cars:
- Smoke opacity levels
- Particulate matter assessment
CO2 vs MOT Emissions
MOT tests don’t directly measure CO2 emissions. They focus on pollutants harmful to human health rather than greenhouse gases.
Regional Variations and Local Authority Requirements
Different UK regions have varying approaches to emissions monitoring and restrictions.
London’s Ultra Low Emission Zone (ULEZ)
ULEZ focuses on NOx and particulate matter rather than CO2, but cleaner cars typically perform better across all emissions categories.
Clean Air Zones
Cities like Birmingham, Leeds, and Bath have implemented Clean Air Zones with different standards. Check local authority websites for specific requirements.
Scotland and Wales Initiatives
Both countries have additional environmental policies that may affect vehicle choice based on emissions data.
Electric and Hybrid Vehicle CO2 Ratings
Electric and hybrid vehicles receive special treatment in CO2 emissions calculations.
Pure Electric Vehicles
Battery-electric vehicles show 0g/km CO2 emissions for official purposes, though this doesn’t account for electricity generation emissions.
Plug-in Hybrids
PHEVs show very low CO2 figures (often 20-50g/km) based on standardised testing that assumes regular charging. Real-world figures vary significantly based on driving habits.
Mild Hybrids
These vehicles typically show modest CO2 reductions compared to conventional engines, usually 10-30g/km lower than equivalent petrol or diesel versions.
How Weather and Driving Style Affect Real-World CO2 Emissions
Your actual CO2 output differs from official figures based on several factors.
Seasonal Variations
Winter driving:
- Cold engines produce more emissions during warm-up
- Increased use of heating and lights
- Reduced tyre pressure affects efficiency
Summer conditions:
- Air conditioning increases fuel consumption
- Better tyre performance and aerodynamics
- Engine reaches optimal temperature faster
Driving Style Impact
| Driving Behaviour | CO2 Impact |
|---|---|
| Aggressive acceleration | +20-40% |
| Excessive idling | +10-15% |
| High-speed motorway driving | +15-25% |
| Stop-start city driving | +10-30% |
| Eco-driving techniques | -10-20% |
Future Changes to CO2 Emissions Regulations
The UK continues evolving its approach to vehicle emissions and taxation.
Planned Changes
2030 Ban: New petrol and diesel car sales end in 2030, with some hybrid exceptions until 2035.
ZEV Mandate: Manufacturers must ensure zero-emission vehicles comprise increasing percentages of their UK sales.
Tax Evolution: Road tax structures may change to reflect new vehicle technologies and environmental goals.
Tools and Apps for Emissions Tracking
Several digital tools help monitor and understand your vehicle’s environmental impact.
Fuel Economy Apps
Apps like Fuelio and Road Trip track real-world fuel consumption, helping estimate actual CO2 emissions compared to official figures.
Government Resources
The Gov.uk fuel economy website provides official tools for comparing vehicle emissions and costs.
Summary
Checking your car’s CO2 emissions in the UK involves several straightforward methods. Your V5C document provides the quickest access, while DVLA’s online service offers 24/7 availability. Manufacturer specifications and independent databases provide additional verification.
Understanding these figures helps you calculate road tax costs, assess environmental impact, and make informed vehicle choices. Remember that real-world emissions often differ from official test figures due to driving conditions and vehicle maintenance.
With the UK’s transition towards electric vehicles and net-zero emissions targets, CO2 figures remain crucial for financial planning and environmental responsibility. Regular checking ensures you stay informed about your vehicle’s impact and any policy changes affecting your costs.
Frequently Asked Questions
How often do CO2 emissions figures change for the same car model?
CO2 figures typically remain constant for a specific model year and engine variant. Changes occur with new model years, engine updates, or when manufacturers switch from NEDC to WLTP testing standards.
Can I reduce my car’s CO2 emissions after purchase?
Minor improvements are possible through regular servicing, maintaining correct tyre pressures, and eco-driving techniques, but you cannot change the official CO2 rating used for tax calculations.
Do CO2 emissions affect my car insurance premiums?
Not directly, but higher CO2 emissions often correlate with larger engines and higher insurance groups, which can increase premiums.
What’s the difference between CO2 emissions and fuel consumption?
They’re directly related – higher fuel consumption means higher CO2 emissions. Petrol produces approximately 2.3kg of CO2 per litre, whilst diesel produces about 2.7kg per litre.
Are WLTP CO2 figures accurate for real-world driving?
WLTP figures are more realistic than previous NEDC tests but still represent controlled laboratory conditions. Real-world emissions typically exceed official figures by 10-40% depending on driving conditions and style.