CO2 Emissions and Motor Cars

What is CO2?   CO2 in the UK UK CO2 and the Motor Car Low Emission Cars

Discussing CO2 emissions generated by motor cars,

The Road to Cleaner Air: Tackling CO2 Emissions in the Automotive Industry

What is CO2?

CO2 Emissions – CO2 is a chemical compound called Carbon Dioxide, and at ambient temperature, it is a colourless gas with a sour taste.

Natrally present in the atmosphere, after time, it absorbs infrared radiation from the Sun and acts as heat trapping a greenhouse gas.

CO2 in its natural form only represents 4% of the earth’s atmosphere and it is known as a trace gas, by contrast by burning fossil fuels, Carbon Dioxide increases. As a result, significantly contributing to the greenhouse gas problem.

Pre-industrial revolution (1720-1800) [9]278ppm -2021 417ppm (parts per million)[10]

Clean air for all

Good CO2

CO2 Emissions – In naturally occurring photosynthesis, plants absorb CO2 from the atmosphere, absorbing sunlight and water, and return carbon to the soil via decomposition. 

Without greenhouse gasses, the Earth would be a frozen ball, so there is a balance to be had.

There are 2,500 gigatons of carbon in the Earth’s soil, 3 times the amount in the atmosphere and 4 times the amount stored in living plants and animals.[2]

Interestingly there are buried pockets of carbon dioxide called Mazuku, accumulated in the ground that can be released through a fissure in the earth, these naturally occurring events can be lethal to human or animal life [3]

Toxic air from a factory

CO2 Safety limits

Despite its negativity, carbon dioxide is not classified as toxic; it is an asphyxiant gas. It becomes dangerous for life when it replaces oxygen in the body. In due time, high concentrations and can cause hypercapnia (poisoning) over a long period.[4]

Authorities regard safe levels of CO2 (UK) to be at an average of 5,000 ppm (parts per million) when outdoors over eight hours.

Whereas 15,000 ppm over 15 minutes indoors, and where there are outdoor readings of a concentrated 400 ppm, this can be higher in high-traffic areas, up to 6-900 ppm.[5]

CO2 in the UK

CO2 Emissions – In 2020, on the Emissions Database for Global Atmosphere Research (EDGAR); ranked the United Kingdom 18th In the world for producing CO2 Emissions.

As a result the UK contributes 314 million tons of CO2 or 0.87% of the world’s greenhouse gasses, or if you wish, Per capita, 4.26 tons.[6] 

On balance, China was responsible for 32.48% of global CO2 emissions in the atmosphere.

Per capita, The Netherlands were 8.4 tons, Norway 6.74t and New Zealand 6.83t.[6]

UK transport is responsible for 24% of the CO2 emissions in the UK, it is to be noted, is down by 22% since 1990; this includes all transport, taxis and cars were 52% of the latter figure [7]

The average UK car (Diesel, Petrol, Hybrid) contribution to CO2 emissions is 119.7 grams per kilometre (g/Km) and with an average of 12,000km (7,600mls) per year 119g/km x12k = 1.42 Metric tons of CO2 per year per car [8].

UK Approach to CO2 and, the Motor Car 

Control zone in city centres

The UK Government is at the forefront of the move towards lower car emissions; and is introducing legislation that bans the sale of new fossil fuel cars from 2030; and will ban all new cars producing any form of CO2 (Hybrids included) by 2035; as a result this means most current Hybrids.

Initially, there was support for switching to a low-emission vehicle with government grants, due to revision this support is now no longer available.

According to current UK government plans; the lower Benefit in Kind (BIK) tax rate; and the Zero Vehicle Exise Duty (VED) will be gradually phased out, and all incentives will end by 2025.[11}

Similarly, Metropolitan Mayors or councils have gone further by introducing LEZ (Low Emission Zone) and ULEZ (Ultra Low Emission Zone); as a result, users will face daily charges for non-compliant vehicles.


Low Emission Cars

If you are concerned about the increase in CO2 levels or perhaps that you want to avoid paying additional taxes. With low-emission cars, there is plenty of choic available. 

  • BEV or Battery Electric Cars have Zero CO2 emissions as a result this means zero, from the tailpipe
  • PHEV or Plugin Hybrid Cars have a petrol engine and one or two electric motors; driven by a battery charged from an outside source. CO22emissions are typically 20-50 g/Km.
  • Full Hybrid cars have a petrol or diesel engine with a smaller electric motor and battery; the two engines switch seamlessly to drive the car charging the battery through regenerative braking.
  • Some advanced models, like the Nissan E-Power, use the petrol engine to charge the battery,which in turn powers the electric motor.  CO2 emissions are typically 90-115 g/Km.
  • MHEV Mild Hybrid electric vehicles are petrol or diesel engines with a small battery and electric motor; in brief, the electric motor assists the conventional engine when cruising, typically advantages on motorways. CO2 emissions are typically 106-139 g/Km.
 CO2 emissions from your car


What percentage of CO2 pollution is from cars?

In the UK in 2020 transport was responsible for 24% of emissions (99 MtCO2e million tonnes of carbon dioxide equivalent) a 19% drop from equivalent figures in 1990. Cars and Taxis were responsible 52% of the Transport total (51MtCO2e)[1]

Which vehicles emit the most CO2?

Cars with a CO2emissions of 255g/Km and higher are deemed to have a High CO2. There are currently 281 cars available to buy that exceed 255g/Km; here are the top 5 :(WLTP)
1/ Rolls Royce Cullinan Black Badge CO2 380g/Km
2/ Rolls Royce Cullinan CO2 377g/Km
3/ FERRARI 812 GTS CO2 373g/Km
5/ Rolls Royce Dawn CO2 372g/Km

How much CO2 does the average car emit UK?

UK Government Targets are CO2 95g /Km or less for cars and CO2147g/Km for vans.
According to WLTP UK Figures, 4,409 cars produce CO2 emissions with an average of CO2159g/Km.
With all listed cars available, including all Zero emissions vehicles (4,734), the average is CO2 148g/Km

What causes high CO2 emissions in cars?

The simple answer is that an internal combustion engine requires fossil fuels, petrol or diesel, to combust inside the engine to produce energy and mechanically drive motion. The bigger the engine, the more fossil fuel is needed to burn.

Fossil Fuels contain carbon and hydrogen atoms; during combustion, the carbon atoms combine with oxygen from the air to produce carbon dioxide and CO2 emissions2emissions.

The composition of the fossil fuel varies in quality, and its crude source, age, refinery process and the mixture of E-Fuels like Ethanol can reduce CO2tail pipe emission.

The new E10 fuel used in the UK is an example of this; with a combination of 10% ethanol and 90% fossil fuel,  and equally important, this can be used without any modification to current engine technology.