CO2 Emissions
What CO2 emissions are and why they’re important
What are CO2 emissions?
Carbon Dioxide, also known as CO2, is a gas in the Earth’s atmosphere. Natural levels of CO2 emission are balanced out in the Earth’s ecosystem through processes such as trees and plants absorbing CO2 during photosynthesis. However, in recent years we’ve increased the level of CO2 emissions through the excessive burning of fossil fuels, including in our cars with petrol and diesel.
Globally the world is trying to reduce the amount of man-made emissions. In the UK, domestic transport remains the largest source of emissions, accounting for 29.1% in 2023, which is why the government's committed to reducing the amount by putting a stop to the sale of new vehicles that are powered by traditional fuels.
With numerous benefits in place for vehicles with lower emissions, when it comes to looking at a new lease, vehicle emissions are an important consideration.
How are CO2 emissions measured?
CO2 is measured by its weight in grams. For a vehicle’s CO2 emissions, the amount of CO2 emitted over a set distance is measured. This is usually done in grams per kilometre, so when you’re looking at cars you’ll see the value written as g/km.
Following the introduction of the ZEV Mandate, delivered by the Vehicle Emissions Trading Schemes Order 2023 (VETS) in Great Britain in 2024, and its recent extension to cover the entirety of the United Kingdom from 2025, 80% of all new cars, and 70% of all new vans are already required to be zero emission from 2030. The existing regulatory framework to 2030 doesn't require any improvements to
CO₂ emissions of new non-ZEVs but rather that they are maintained at 2021 levels.
There are a few different ways that emissions are currently being measured and have been in the past, outlined below:
The New European Driving Cycle (NEDC) rating of a car was historically used to give the vehicle its CO2 emission rating.
This measurement was reached through a series of tests in the laboratory. It was criticised for not reflecting real life driving conditions, as the tests had not been updated in nearly 20 years and the NEDC test cycle finally expired in 2018 when it was replaced by the new WLTP test.
These tests are designed to provide ratings that reflect driving conditions in the real world, and are run over a series of different driving cycles, for a longer time and more realistic driving temperatures.
To see a more extensive breakdown of the WLTP tests take a look at this blog.
The Real Driving Emissions (RDE) test measures the pollutants from a vehicle whilst it's being driven on a road, rather than in laboratory conditions.
This test doesn't replace the WLTP test but works alongside it, to provide you with additional data on a vehicle's emissions.
CO2 is not currently measured by RDE tests, but may be in the future.
The Euro 6 is a revision of the Euro 1, an EU target for vehicle emissions.
It measures the other emissions, apart from CO2, that a car produces. These include: carbon monoxide, nitric oxide, nitrogen oxide, hydrocarbons, and particulate matter like soot.
When you’re looking for your next lease car you don’t need to worry about this measurement, as this is only given to a car to show it's meeting the European standards.
Post-Brexit UK is likely to keep current standards but not accept new ones from the EU. Instead the UK government will continue to set its own goals and restrictions in line with more general CO2 and emission reduction targets.
MOT testing
Vehicles are also tested for their emission levels at their MOTs.
If you're leasing, and your lease is for less than 3 years then you won't need to worry about this.
If your lease is for longer than 3 years your car will need a MOT. The emissions will be rated and if they're higher then they should be, could cause the MOT to fail, but this is very rare on such a new vehicle.
If you're leasing a vehicle then you won't need to worry about the road tax as this is covered by the funder for the duration of your lease.
However, if you own the vehicle then the CO2 emissions will affect the road tax you pay.
If you're using a car provided to you by your employer, then you'll have to pay company car tax.
This is in part based on the CO2 emissions produced by the vehicle. Our Guide to Company Car Tax explains in full how the emission rating is taken into account.
CO2 and low emission zones
With us all becoming increasingly aware of the impact that vehicle emissions have, more and more cities are putting plans into action to try and reduce the amount in their city centres.
A lot of cities are following London's lead and putting in place Low Emission Zones (LEZ) or Clean Air Zones (CAZ), where vehicles that don't meet the emission standards outlined, have to pay a charge.
If you're looking at a new lease vehicle and work in a city where there is a LEZ or CAZ area, then you might want to look at the criteria for these and pick a car where you won’t be charged a higher rate.
How can I reduce my CO2 emissions?
There are a number of things you can try to reduce your CO2 emissions on your current vehicle, including:
- Use better fuel
- Add cleaning agent to the fuel tank every now and then
- Change the oil and make sure you use the right grade
- Change the air filter
- Keep up to date with services
- Check tyre pressure and keep at an optimum level
- Turn the air conditioning off
- Remove any roof and bike racks when not using
- Don’t sit with the engine running
- Drive with consideration and avoid hard accelerating
Alternatively, if you're looking for a new car then you might want to consider a hybrid or even a fully electric vehicle. Check out our top offers on these or have a look at our guide to electric vehicles for more information on them.
If you have any questions about the CO2 emissions on a car you’re interested in, then please get in touch on 03302210000.