Euro emission standards set the maximum levels of pollutants that new vehicles can produce. They've been progressively tightened since 1993, and they now determine whether your car can drive in clean air zones, how much road tax you pay, and how easy it is to sell.
Here's what each standard means and how to check which one your car meets.
The Euro standards at a glance
| Standard | Dates | Petrol | Diesel | Key Change |
|---|---|---|---|---|
| Euro 1 | Jul 1992 | All petrol cars | All diesel cars | Catalytic converters mandatory |
| Euro 2 | Jan 1997 | All petrol cars | All diesel cars | Tighter CO and HC limits |
| Euro 3 | Jan 2001 | All petrol cars | All diesel cars | On-board diagnostics (OBD) required |
| Euro 4 | Jan 2006 | All petrol cars | All diesel cars | 50% NOx reduction for diesel |
| Euro 5 | Sep 2009 | All petrol cars | All diesel cars | Diesel particulate filters mandatory |
| Euro 6 | Sep 2015 | All petrol cars | All diesel cars | Dramatic NOx reduction, real-world testing |
Each standard applies to new type approvals first, then to all new registrations. A car's Euro standard is determined by when it was first registered, not when it was manufactured.
How to check your car's Euro standard
The quickest way is to use our free car check. Enter the registration number and we'll show you the vehicle details including its first registration date, fuel type, and CO2 emissions — all the information you need to determine the Euro standard.
As a general guide based on first registration date:
Petrol cars:
- Before January 2001 → Euro 1 or Euro 2
- January 2001 – December 2005 → Euro 3
- January 2006 – August 2009 → Euro 4
- September 2009 – August 2015 → Euro 5
- September 2015 onwards → Euro 6
Diesel cars:
- Before January 2001 → Euro 1 or Euro 2
- January 2001 – December 2005 → Euro 3
- January 2006 – August 2009 → Euro 4
- September 2009 – August 2015 → Euro 5
- September 2015 onwards → Euro 6
Some manufacturers adopted newer standards ahead of the mandatory dates, so a car registered in early 2015 might still be Euro 6 compliant if the manufacturer certified it early.
Why Euro standards matter
ULEZ and clean air zones
This is the most immediate practical impact. London's Ultra Low Emission Zone (ULEZ) and other clean air zones across the UK use Euro standards as their entry criteria:
- ULEZ (London) — Requires Euro 4 for petrol (roughly 2006+) or Euro 6 for diesel (roughly September 2015+). Non-compliant vehicles pay £12.50 per day.
- Birmingham Clean Air Zone — Same Euro 4/Euro 6 requirements. Non-compliant cars pay £8 per day.
- Bristol Clean Air Zone — Euro 6 diesel or Euro 4 petrol required in the central zone.
- Other cities — Bath, Bradford, Sheffield, Newcastle, and others have implemented or are planning zones with similar requirements.
Check your vehicle's compliance instantly with our ULEZ check.
Road tax (VED)
Vehicles registered after April 2017 pay a flat-rate VED of £190 per year (2024/25 rates) regardless of emissions, with a first-year rate based on CO2. But for cars registered between March 2001 and March 2017, road tax is banded by CO2 emissions — and cleaner Euro 5/6 engines generally produce lower CO2 than their Euro 3/4 predecessors. See our complete car tax rates guide for the full band-by-band breakdown.
Resale value
Euro standard increasingly affects how easy a car is to sell and what it's worth. A diesel car that doesn't meet Euro 6 is effectively locked out of major cities, which reduces its appeal to a significant portion of buyers. Use our free valuation to see how your car's value compares to the market.
Future restrictions
Clean air zones are expanding. More cities are introducing or tightening restrictions, and the trend is towards stricter requirements. A Euro 6 diesel is compliant today, but future Euro 7 standards (expected in the coming years) may shift the goalposts again.
Euro 6: the current standard
Euro 6 has been mandatory for all new cars since September 2015. It introduced:
- Dramatically lower NOx limits — Diesel NOx limits dropped from 180 mg/km (Euro 5) to 80 mg/km (Euro 6)
- Real Driving Emissions (RDE) testing — In addition to lab tests, cars must meet emission limits during on-road testing (introduced in Euro 6d-TEMP and Euro 6d)
- Selective Catalytic Reduction (SCR) — Most Euro 6 diesel cars use AdBlue (a urea-based fluid) to reduce NOx emissions
Euro 6 has several sub-categories:
- Euro 6b — Lab testing only (September 2015)
- Euro 6c — Updated lab test cycle (WLTP) from September 2018
- Euro 6d-TEMP — Added on-road (RDE) testing from September 2019
- Euro 6d — Full RDE compliance from January 2021
All sub-categories meet the minimum requirements for ULEZ and clean air zones.
The diesel dilemma
Diesel cars have been most affected by tightening Euro standards. The key thresholds:
- Pre-Euro 6 diesel (before September 2015) — Cannot enter ULEZ or most clean air zones without paying a daily charge. Resale value has dropped significantly.
- Euro 6 diesel — Currently compliant everywhere, but carries a stigma that affects residual values.
- Euro 4 diesel — Still a practical car outside of clean air zones, but limited urban access.
If you're considering buying a diesel car, check the ULEZ compliance and read our guide on whether your car is ULEZ compliant to understand the full implications. Consider whether you'll need to drive in or near any clean air zones. If you will, Euro 6 is the minimum standard you should consider.
Petrol cars have it easier
Petrol cars face far less restrictive requirements:
- Euro 4 petrol (roughly 2006+) — Compliant with ULEZ and all current UK clean air zones
- Euro 3 petrol (2001–2005) — Not ULEZ compliant, but unaffected outside London and other zones
This lower threshold means most petrol cars from the last 20 years can drive freely in clean air zones, making them a simpler choice for urban buyers.
Electric and hybrid vehicles
Battery electric vehicles (BEVs) produce zero tailpipe emissions and are automatically exempt from all emission-based charges. Plug-in hybrids (PHEVs) are generally Euro 6 compliant and meet clean air zone requirements when running in hybrid mode.
If you're checking a hybrid vehicle, our free car check will show the fuel type and emissions data to confirm its status.
Safety recalls and emissions
Some manufacturers have issued safety recalls related to emissions equipment — particularly diesel particulate filters (DPFs), AdBlue systems, and EGR valves. Check for outstanding recalls with our recall check to ensure any emissions-related fixes have been applied.
The bottom line
Your car's Euro emission standard determines whether you can drive in clean air zones, affects your road tax, and influences resale value. The most important thing is knowing which standard your car meets.
Run a free car check to see your vehicle's details, then check your ULEZ compliance to see whether you're affected by any restrictions. If you're buying a used car, prioritise Euro 6 for diesel or Euro 4+ for petrol to avoid any current or future clean air zone charges.