See all Motoring AdviceVehicle pollution is a big focus for eco campaigners, while a reduction in car exhaust emissions is the chief driver behind the European Union's campaign to end the sale of new combustion-engined cars from 2035 onwards.
However, while the EU ban will eventually outlaw the sale of brand-new combustion-engined cars in showrooms, there are still going to be plenty of petrol and diesel models driving around as buyers gradually make the switch to all-electric, zero-emissions vehicles. Before that happens, you might like to know exactly what your car’s emissions are, so here's how to find out.
First things first, you've probably seen reference to a car's carbon dioxide (CO2) emissions in a brochure or on a website. This figure is recorded under test conditions and will largely determine the rate of tax that a car will face through its lifetime. Of course, the lower the figure, the lower the tax rates, and you'll find that cars with low emissions figures will also deliver strong fuel economy. However, this figure is produced during laboratory tests, so while it's useful to compare cars that have all been tested under the same regime, this figure is likely to be poorer when it comes to everyday driving.
Something that a car's official CO2 figure doesn't take into consideration is other emissions from the tailpipe - noxious gases and, in the case of diesels, soot and micro particles. These CO2 figures are exclusively for the car when it's driving, too; there are further emissions produced during the car's manufacture, when raw materials are extracted, and also during the transportation of the car from factory to a dealership, which could potentially be on opposites sides of the globe.
If you just want to work out your car's everyday emissions, you can do it by estimating your CO2 based on the amount of fuel you use. The simple formula is that burning one litre of unleaded petrol creates 2.31kg of CO2, so if you fill your car up with 40 litres of fuel, that's 92.4kg of carbon dioxide created when it is all used up. The CO2 figure for diesel models is 2.68kg, so the total for a 40-litre tank would be 107.2kg.
There are plenty of websites available that allow you to calculate your car's carbon footprint. These will take into consideration your car's emissions and the mileage you cover every year, while some also account for the emissions generated by the car's construction and delivery, as well as the pollution created by the processing and refining of the crude oil into petrol or diesel. Many carbon footprint calculators also work for electric vehicles; while EVs don't produce CO2 during driving, there are still emissions in their construction, the sourcing of battery chemicals and the generation of the electricity that they're charged with.
Some sites offer you the opportunity to do some carbon offsetting. This sees you pay a fee to cover the cost of tree planting, the idea being that the trees planted can absorb the CO2 that is emitted by your car. Sites such as reforestnation.ie allow you to set up a monthly subscription to cover your regular commute, or you can just offset a single journey.