CO2 · 1,328 cars covered
Clean cars. Dirty cars. Real numbers.
Official WLTP CO2 figures from the EU type-approval register, matched to UK fleet data. UK fleet averages, cleanest 30, dirtiest 30, and what your tax band actually means.
Petrol fleet avg
148g/km
CO2 · new-car · DfT 2023
Diesel fleet avg
155g/km
CO2 · new-car · DfT 2023
UK fleet CO2 averages (g/km WLTP) — new-car register · DfT / SMMT 2023
Petrol
148g
Diesel
155g
Hybrid (PHEV)
42g
Electric (BEV)
0g
tail-pipe
Fleet averages are for new-car registrations. In-service cars (older models) typically emit more due to higher-CO2 legacy vehicles in the registered parc. EV figures are tail-pipe only — upstream generation emissions are not included.
Petrol vs Diesel CO2
Modern diesel still emits more CO2 per km than petrol — on paper.
The UK fleet average for a new diesel car is 155 g/km versus 148 g/km for petrol. Diesel produces less CO2 per litre of fuel burned, but the cars tend to be heavier or driven in larger segments where efficiency is lower. Hybrids cut that to 42 g/km under WLTP test conditions — though real-world figures vary with how often the battery is charged.
- New petrol avg
- 148 g/km
- New diesel avg
- 155 g/km
- New hybrid avg
- 42 g/km
- BEV tail-pipe
- 0 g/km
Lowest CO2
Cleanest 30 cars.
Ranked by official WLTP CO2 (g/km). Plug-in hybrids and EVs use their registered WLTP figure. Electric cars appear separately — 0 g/km tail-pipe makes comparison with combustion engines misleading.
| # | Car | CO2 (g/km) |
|---|---|---|
| 01 | BMW X1 Xdrive25e M Sport Auto | 17 |
| 02 | BMW 225 | 18 |
| 03 | Levc TX Vista Comfort Plus | 19 |
| 04 | Levc TX Vista | 19 |
| 05 | Levc TX | 19 |
| 06 | Lexus NX | 23 |
| 07 | mercedes-benz__250 | 24 |
| 08 | lexus__rx-450h-f-sport-cvt | 25 |
| 09 | Lexus RX 450h Luxury Cvt | 25 |
| 10 | lexus__rx-450h-premier-cvt | 25 |
| 11 | Lexus RX | 25 |
| 12 | Lexus Rx300 | 25 |
| 13 | lexus__rx400-h-se-cvt | 25 |
| 14 | Lexus Rx400h | 25 |
| 15 | volvo__xc60-inscrpt-pro-t8-phev-awd-a | 25 |
| 16 | Volvo Xc60 Momentum B5 Mhev Auto | 25 |
| 17 | volvo__xc60-r-design-t8-phev-awd-auto | 25 |
| 18 | BMW 330e M Sport Auto | 28 |
| 19 | BMW 330e SE Pro Auto | 28 |
| 20 | BMW 330e Sport Pro Auto | 28 |
| 21 | BMW 330 | 33 |
| 22 | Audi E Tron | 34 |
| 23 | volvo__xc90-inscript-pro-t8-phev-a-a | 35 |
| 24 | Volvo Xc90 R Design B5 Mhev Awd Auto | 35 |
| 25 | Lexus Rx450h | 43 |
| 26 | BMW X3 Xdrive30e M Sport Auto | 47 |
| 27 | BMW X5 Xdrive45e M Sport Auto | 53 |
| 28 | Mitsubishi Eclipse Cross Exceed 4x4 Cvt | 56 |
| 29 | Mitsubishi Eclipse | 56 |
| 30 | Ford Explorer | 74 |
Source: EEA CO2 monitoring database (type-approval WLTP). "vs fleet" = delta from UK fuel-type fleet average.
Highest CO2
Dirtiest 30 cars.
Cars with the highest recorded WLTP CO2. Typically performance models, large SUVs, and heavy diesel vehicles. Figures are type-approval — real-world may differ.
| # | Car | CO2 (g/km) |
|---|---|---|
| 01 | Mercedes Benz X | 456 |
| 02 | Lamborghini Aventador | 448 |
| 03 | Ferrari 812 Superfast S A | 373 |
| 04 | Rolls Royce Phantom | 356 |
| 05 | Rolls Royce Ghost | 355 |
| 06 | Mercedes Benz A | 344 |
| 07 | Mercedes Benz GT | 344 |
| 08 | Bentley Flying Spur | 340 |
| 09 | Lamborghini Huracan | 332 |
| 10 | Dodge Caliber | 322 |
| 11 | dodge__journey | 322 |
| 12 | Dodge Nitro | 322 |
| 13 | Dodge Ram | 322 |
| 14 | Nissan GT R | 316 |
| 15 | Mercedes Benz 500 | 313 |
| 16 | Aston Martin Vanquish | 312 |
| 17 | Aston Martin Dbs | 306 |
| 18 | Chevrolet Aveo | 304 |
| 19 | chevrolet__camaro | 304 |
| 20 | Chevrolet Captiva | 304 |
| 21 | Chevrolet Cruze | 304 |
| 22 | Chevrolet Kalos | 304 |
| 23 | Chevrolet Lacetti | 304 |
| 24 | Chevrolet Matiz | 304 |
| 25 | Chevrolet Orlando | 304 |
| 26 | Chevrolet Spark | 304 |
| 27 | chevrolet__tacuma | 304 |
| 28 | Chevrolet Trax | 304 |
| 29 | Maserati Levante D V6 Auto | 299 |
| 30 | Mercedes Benz SL | 299 |
Source: EEA CO2 monitoring database (type-approval WLTP). "vs fleet" = delta from UK fuel-type fleet average.
Road Tax
CO2 → VED band.
What your car actually costs to tax.
First-year Vehicle Excise Duty (road tax) is set by CO2 band for cars registered from April 2017. The jump between band G (≤150 g/km) and band H (151–170 g/km) is steep — from £270 to £680. Get below 150 g/km and you're in a significantly cheaper bracket.
Standard annual rate after the first year is £190 (2024/25) for most cars, regardless of CO2. Rates shown below are first-year only. Always verify current rates on GOV.UK.
| Band | CO2 | First-year rate |
|---|---|---|
| A | 0 g/km | £0 |
| A | 1–50 g/km | £10 |
| B | 51–75 g/km | £30 |
| C | 76–90 g/km | £130 |
| D | 91–100 g/km | £165 |
| E | 101–110 g/km | £185 |
| F | 111–130 g/km | £220 |
| G | 131–150 g/km | £270 |
| H | 151–170 g/km | £680 |
| I | 171–190 g/km | £1,095 |
| J | 191–225 g/km | £1,650 |
| K | 226–255 g/km | £2,340 |
| L | Over 255 g/km | £2,745 |
First-year VED rates for cars registered from April 2017. Rates subject to change — verify at GOV.UK.
Data sources
Where these numbers come from
CO2 figures are sourced from the European Environment Agency (EEA) CO2 monitoring database, which records WLTP type-approval figures submitted by manufacturers for every new passenger car registered in EU and UK markets. The dataset is published annually under a Creative Commons CC BY 4.0 licence.
UK fleet averages are from the Department for Transport new-car CO2 reports and SMMT annual data. These cover new registrations — the in-service fleet (which includes older, higher-CO2 cars) will show higher real-world averages.
Coverage: 1,328 of 1,984 tracked models have matched CO2 data. Cars with no public type-approval figure (older models, grey imports, low-volume specials) are excluded rather than estimated. Better partial coverage than full-fleet guesswork.
Data last fetched: 2026-06-06. WLTP figures ≠ real-world driving. All CO2 is tail-pipe; upstream / well-to-wheel not included. VED rates shown are for guidance — always verify at GOV.UK before purchasing.