Diesel cars: Should I stick with one or go back to petrol

In 2008, when the motor tax system was changed from the old by-engine-capacity rates to the current Co2-based rates, we became a diesel society. Prior to that, three quarters of cars sold in Ireland came with a petrol engine. Now, that position is reversed and petrol accounts for less than 30 per cent of new car sales, although in 2015 that gap has narrowed a little. With the scandal surrounding diesel right now though, many car buyers are worried about which fuel type to choose, so here is a handy guide to everything you need to know about diesel power and what’s happening to it right now.

Does my diesel car need to be recalled?

Only if it is a Volkswagen, Seat, Audi or Skoda made between 2008 and 2013 and using a 1.2, 1.6 or 2.0-litre diesel engine. You’ll be contacted by post if you have one of those cars, and invited to bring it in to a dealership to have its software adjusted. Owners of other diesel engined cars need not worry, for now.

Does diesel cause more damage to the environment?

Diesel cars 4It depends on which sort of damage you mean. The scandal surrounding Volkswagen is to do with emissions of nitrogen oxide (NOx), of which diesels emit much more than petrol engines. It’s nasty stuff, NOx – contributing to serious lung and respiratory problems and also a major cause of asthma.
Petrol engines though, pound for pound, emit more carbon dioxide (Co2) and it is Co2’s role in climate change that has caused all of Europe’s vehicle tax regimes to be based on emissions of carbon dioxide. So basically, in choosing between petrol or diesel you’re choosing between pollution that’s a problem at the local level, and pollution that’s a problem on a global scale.
There’s a third form of pollution – particulates. These are microscopic particles of soot that are not fully burned during the combustion process. They can be filtered from the exhaust gas (by a particulate filter) and are usually associated with diesel engines. Research shows, though, that some petrol engines using direct fuel injection (which is most modern petrol engines) are as bad as diesels for particulate emissions, and they are highly carcinogenic.

Will road tax rates go up?

There’s a Budget coming up, so road tax rates are always liable for adjustment. As for whether some diesel cars will become more expensive to tax, that seems as if it’s at least possible. Thanks to the recent scandal, the European Union is setting about making its official fuel and emissions testing systems much more stringent, including an element of ‘real-world’ driving conditions – up to now, almost all fuel and emissions tests are done in the laboratory, to ensure consistent results.
If that goes ahead, then it’s likely that cars will appear to be more thirsty than they are now. Experts such as eco-watchdog Transport and Environment claim that some cars have emissions and fuel consumption that are 50 per cent worse in the real world than they are in the lab tests. If the new, more severe, tests reveal that to be the case then cars are going to come with higher official Co2 figures and, then, you’re going to pay more motor tax.

Will I be liable for back taxes?

That’s a complicated one. If some car makers, as has been alleged, can be shown to have been using illegal components in their official tests, then there could be a liability for underpaid tax, both on the purchase price of the car and for its annual motor tax. It’s very unlikely, though, that the individual consumer would be hit for those taxes. It’s much more likely that the car maker in question would have to foot the bill.
Incidentally, specifically in the VW case, it’s not yet been proven (at the time of writing) that Volkswagen Group cars were cheating on their European fuel and emissions tests. So far, that’s only been shown to be the case in America.

Will the value of my diesel car go down?

Diesel cars 2If it’s one of the ones that has been caught cheating, probably yes, at least in the short term. Certainly if some cars have to be sent back for re-testing, and they are shown to have higher Co2 levels than was previously thought, then the higher motor tax rating would be enough to push their values down at least a little.
As for diesel cars in general, it’s a little unclear. There’s a massive furore over diesel engines right now, which will at the very least dampen their appeal a little. But in general, unless there’s a major move in motor tax rates, they’re unlikely to dip by much or for very long. Irish buyers buy with their wallets, not their lungs, so a car that’s generally more economical and has cheaper tax will always be popular.

If petrol and diesel are both bad for the environment, how can I drive with a clear conscience?

You could go electric. Nissan is about to launch an updated version of the Leaf hatchback which will boast a potential 250km range on one charge. That’s significantly better than the 160km it first launched with and it makes pure battery power a much more viable option for a larger number of people.
Plus, if you wait for a couple of years, there are car companies queuing up to offer battery electric vehicles that can go for a claimed 500km between charge-ups and that is a figure that would suddenly make electric motoring possible for all.
In the meantime, your best bet would probably be to go for one of the plugin hybrids currently coming onto the market. Those can operates on clean electric power for short journeys in town (usually of up to 50km or so) where air quality issues are at their most pressing, but they have a conventional engine on board (generally a petrol one) for longer journeys. If nothing else, they’re a good half-way house between where we are now and where we want to get to.