petrol or diesel?
Changes in legislation, concerns over public health and the transparency of emissions testing, has caused many to question how clean diesel engines are and whether it’s the right choice for them.
Why are diesel engines under the spotlight?
Oxides of Nitrogen (NO and NO2) are produced as a by-product of internal combustion (in engines). These Oxides of Nitrogen – NOx gases as they are known – and related hydrocarbons and other pollutants have been linked to respiratory problems, smog and poor air quality.
Whilst diesels produce less CO2 on average than petrol engines, they produce more NOx. In modern diesels, Diesel Exhaust Fluid (DEF) – also known as AdBlue – is used within a Selective Catalytic Reduction (SCR) system to convert NOx back to Nitrogen and Oxygen. Older diesels, built before the latest EU6 emission standards were introduced, can produce much more NOx and particulates than the EU6 diesels, as they do not have this SCR technology. In addition, since 2006 Jaguar Land Rover diesel vehicles have been fitted with particulate filters, removing 99% of all particulates from the exhaust.
Jaguar Land Rover’s commitment to sustainable driving however means we are pro-actively producing some of our cleanest engines to date, dramatically reducing our NOx emissions and removing the need to compromise a cleaner choice of vehicle for one with a defined performance.
- From September 2015, all of our diesel engines built for the EU and EEA markets, are fitted with Selective Catalytic Reduction treatment which uses the urea-based liquid AdBlue, to convert Nitrogen Dioxide into Nitrogen, Oxygen and water. This exhaust after-treatment converts up to 98% of NOx gases produced by diesel engines, meaning a significantly reduced impact on the environment.
- Filtering technology fitted as standard to all of our diesels, removes up to 99% of all soot particles before they leave the exhaust. The Diesel Particulate Filter does this by extracting and storing particles until they are burnt away automatically and the filter is emptied.
- All of our EU and EEA diesel engines from September 2015 meet tough EU6 emissions regulations, meaning they are so clean they can pass freely through the Ultra Low Emission Zones that will enforce a financial penalty on drivers emitting high levels of pollutants from their vehicles.
What’s the difference between Petrol and Diesel?
Diesel cars deliver an effortless, relaxing drive because of low-speed torque. The narrow power band allows you to change up through the gears earlier and generate meaningful acceleration, making activities such as towing or carrying a large number of passengers much easier.
There has been a misconception that diesel engines are slower, noisier and more expensive to run than petrol vehicles. However engineering advancements and technologies now in-built in diesel engines, means the difference between the two is now barely identifiable.
The widely spread power band in a petrol engine typically requires higher engine speeds to deliver similar torque as a diesel, but the top-end power of a petrol offers a smooth and responsive drive which some drivers prefer.
Which engine is right for me?
Before purchasing any vehicle, you should take into consideration your usual driving habits. Diesels come into their own on longer journeys at higher speeds, but aren’t necessarily the best choice if your usual drive consists of shorter journeys or regular stopping and starting while held up in traffic in a town or city.
If you are driving 12,000 miles a year or more, a diesel is likely to be the most cost-effective choice. The higher energy density of the fuel and the way energy is released during combustion means diesel can offer a greater return on mileage.
The Diesel Particulate Filter (DPF) that collects soot particles in the exhaust and prevents them entering the atmosphere, requires the exhaust to reach a sufficiently high temperature - achieved through driving at a sustained speed and distance - to burn off the collected contaminants.
If this is not a likely occurrence in your day-to-day driving, and travel tends to consists of short sharp bursts of acceleration and braking, a petrol or hybrid engine may be a better choice for you.
The results so far
Jaguar Land Rover has invested £1 billion at our state-of-the art engine manufacturing centre to develop smaller, lower emission diesel engines.
These developments have yielded remarkable results; between 2007 and 2015 we’ve reduced the CO2 emissions from our European fleet vehicles by 32%.
In addition, between 2004 and 2016, our expert engineers have managed to reduce our NOx emissions by 90%.