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The Truth About Diesel

There has been a lot of coverage in the media recently surrounding diesel, most of which has been negatively portraying the fuel and the option of owning/leasing a diesel-powered vehicle. At TFS, we wanted to explore this and give you an insight into the truth surrounding the topic along with the up-to-date facts about diesel. What you can expect from this post is information on the rise in popularity of diesel, some reasoning as to why this perception changed and the current facts about the fuel. We hope to clarify some of the misconceptions people may have made following the negative press and instead, inform you of the facts on diesel right now, allowing you to make your own judgements. Diesel was a popular option for a long time. Until recently, in fact, a diesel engine represented green progress, intelligent science and a superior technology. The core of the engine operated in a way that the diesel combustion cycle yielded a much leaner fuel-air mixture, this can operate at maximum efficiency, as opposed to gasoline engines. Because diesel fuel is more energy-dense than gasoline, it was made aware to the public that this modern diesel emitted lower CO2 emissions in contrast to gasoline engines; this became one of the main attractions of diesel cars to consumers. Initially what gave European diesel engine manufacturers a big competitive advantage, was the promotion that this fuel lowered overall carbon emissions. For some time, the price was lower for diesel than it was for unleaded and the tax rate was also significantly lower for diesel-powered passenger cars.

Diesel and the Media

Where did it go wrong for diesel in the media? Most issues surrounding diesel fuel were no greater than those surrounding unleaded petrol, however, Volkswagen caused outrage when the truth about their diesel-emissions tests finally came out. After years of VW promoting ‘Clean Diesel’ as an alternative to electric and hybrid cars, the truth emerged about just how Volkswagen could give their diesel cars this title. It began when Volkswagen installed emissions software on over half a million diesel cars in the USA, as well as roughly 10.5 million more worldwide. This software allowed them to sense the individual parameters of an emissions drive cycle that was set by the Environmental Protection Agency. This software had been renamed as ‘defeat devices’, detecting throttle, steering and other inputs that are used to test the switch between two operating modes. When in test mode, these cars are fully compliant with all of the federal emissions levels, but when drove normally, this software switched to the separate mode. This separate mode significantly changed fuel pressure, exhaust-gas recirculation, injection timing and in some models, the amount of urea fluid sprayed directly into the exhaust. Although this mode was more than likely to provide higher mileage and power, it also permitted heavier nitrogen-oxide emissions, up to 40 times higher than the federal limit. This didn’t mean every car emitted 40 times over the limit, some cars may have emitted just a few times more, but this depended on the driving style and load. Once it was made aware what VW had been doing, refunds/compensation were offered to all customers involved in the scandal.

Although this is not the sole reason for the popularity and demand for diesel to decline, incidents such as these are usually a catalyst for other media outlets to also negatively report on the topic in question. Much more recently, there have been many reports on the sales of diesel cars falling by around 25% in January this year compared to January 2017. In November of last year, the government did announce that customers purchasing new diesel cars, will face a one-off tax increase in April, unless the vehicle has met the higher standard on emissions. However, it is important to point out that neither diesel or unleaded petrol cars are being promoted as clean cars and this is clear from the government’s long-term goal of banning the sale of new cars running only on diesel or petrol by 2040. In fact, sales of alternatively fueled vehicles, including electric cars, have actually increased by 23.9%. However, this is still only accounting for 5.5% of the overall market, so right now diesel and petrol cars will remain the market leaders; but what are the facts about both fuel types when comparing them against each other?

Benefits of Diesel

For a long time the popularity of diesel vehicles benefitted from the lower car tax and the message of ‘decreasing air pollution’, in comparison to petrol cars. Now that this has changed recently, what are the benefits of diesel? Diesel cars tend to have a better fuel economy, so even though it may cost a fraction more, typically the fuel will go further. This is because the more miles you do with a diesel vehicle, the more you can actually save from the better fuel economy. A Which? test found that, on average, diesel cars are more efficient by around 8 mpg; this may not sound like a lot, but when hearing that it can save around £200 per year, it sounds more appealing. Diesel tends to be a great option for those who drive longer distances, particularly regular motorway driving. Those looking for a more runaround type of car, may steer clear of a diesel vehicle as they are fitted with a DPF, diesel particulate filter; this can clog up if the car is not driven at motorway speeds and can be costly to fix. With car leasing, this is unlikely to be a worry as this happens over quite some time, which is avoidable when choosing to lease a vehicle, rather than committing to purchasing a car outright. Along with this, diesel cars also prove a popular option for vehicles that need to tow, as the engine provides a significant amount of torque (pulling power) meaning that on average, towing can be done with more ease than a petrol powered car. With regards to owning a vehicle, generally right now, petrol cars seem to have the competitive edge; this is because at the moment, petrol cars are cheaper to purchase, maintain and run. However, when choosing to lease a vehicle, it is important to think about which fuel engine will benefit your personal vehicle preference/style of driving more. For example, if it is for work purposes that involve you driving often, long distances and/or motorway driving, leasing a diesel powered engine is likely to have more benefits than an unleaded petrol car. If you are simply looking for a car that gets you from A-B, petrol may be the way to go.

Diesel and Health

Now that we have compared the two, it’s time to consider whether diesel cars are always the biggest health hazard, like they are being portrayed currently. Well the straightforward answer is, it depends on the individual vehicle. Those within the diesel industry insist that modern diesel-powered engines are very clean and can play a crucial role in assisting to cut carbon dioxide emissions. The truth behind the matter, isn’t that simple; although it is a fact that some diesel engines do produce less toxic emissions than some petrol engines, it seems that overall petrol does remain the cleaner option. Both diesel and petrol engines convert the chemical energy into mechanical power by burning the fuel, but they do this in different ways. In principle, a diesel engine should use less fuel, which means less carbon dioxide is produced than a petrol engine that has the same output of power. However, the fact of the matter is diesel engines produce a higher level of particulates; these are microscopic pieces of soot that are left over from following the combustion process. Along with this, diesel engines do produce nitrogen oxides (NOx). This is controlled by the current European emissions standard that have strictly limited how much of this can be produced. It was pointed out that if you look at the cleanest 10% of diesel cars and the dirtiest 10% of petrol cars, the petrol vehicles will have double the NOx emissions of the diesel cars. When taking this point, it does mean that some diesel models do compare better to their petrol equivalents. Some petrol engines are now trying to compete with the efficiency and economical benefits of diesel engines. This means that these petrol-powered engines will now produce a higher level of particulates too, meaning there is a risk that petrol engines may become dirtier. The argument as to whether petrol or diesel engines are the cleaner option is much more complex than first anticipated, but it can only be positive that the question is being asked. If it challenges the current issues faced with petrol and diesel engines, the plans for change and improvement will inevitably emerge. For instance, thanks to the recent introduction of a mandatory on-road emissions test for all new vehicle models in the EU that came in-force last September, this process should begin to lower overall emission levels, which is a step in the right direction for the good of the environment and for us consumers.

Diesel Vehicle Tax

Now that the main issues raised in the media about diesel have been discussed, what might be useful to understand is more about the tax increase on diesel vehicles. The way in which the media has reported on the diesel vehicle tax has confused many on what the new legislation is. If you are unsure, this should clarify what the government have put in place. Drivers of diesel cars that do not meet the predetermined emissions standard, will be required to pay car tax a band higher than what they are currently paying from April 2018. By this time, if the cars do not meet the Euro 6 emissions standard in the real-world driving conditions lab, then the cost will be increased. Below you can find the new rates set to be introduced in April 2018:

1 - 50 g/km CO2 = 2018 Rate: £25
51 - 75 g/km CO2 = 2018 Rate: £100
76 - 90 g/km CO2 = 2018 Rate: £120
91 - 100 g/km CO2 = 2018 Rate: £140
101 - 110 g/km CO2 = 2018 Rate: £160
111 - 130 g/km CO2 = 2018 Rate: £200
131 - 150 g/km CO2 = 2018 Rate: £500
151 - 170 g/km CO2 = 2018 Rate: £800
171 - 190 g/km CO2 = 2018 Rate: £1,200
191 - 225 g/km CO2 = 2018 Rate:£1,700
226 - 255 g/km CO2 = 2018 Rate: £2,000

There has been multiple tax changes recently that have focused around CO2 emissions, however, they do not tackle the NOx issue as of yet; this is why some diesel vehicles may avoid this extra cost.

It is important to remember that although headlines can sway public opinion, researching into the matter individually can give a fuller understanding of the situation. Although it is clear that there is truth in a lot of the media coverage surrounding diesel vehicles, on the other hand, there is a lot more to the stories when taking a closer look. Both diesel and petrol engines have positive and negative aspects, but ruling out one or the other is not the answer. Working towards a majority of alternatively powered motors in the future is not as far away as we may think and it is reassuring to know that plans are already underway. However, with the situation as it is now, the best thing to do is look into which vehicles are the most suited to your own personal needs. As pointed out earlier, diesel and petrol engines can be better for varied driving purposes, therefore looking into the finer details or seeking professional advice can be the most beneficial.

TFS offer personal car leasing as well as business car leasing with both petrol and diesel engine options. If you are considering leasing a vehicle have a look at our best deals or contact us if you have any specific questions, we would be happy to help.

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Posted on 7th February 2018 at 2:47 PM

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