Today, we continue with the occasional series of bonus articles which are not about specific vehicles, but motoring related topics, started back in June. The first of these was about the London Ultra Low Emission Zone, which you can read underneath.
In the pictures below, you will see two Chevrolet Cruzes that I used to own. The cars were virtually identical, as they were both five door hatchbacks with largely the same standard equipment on the LT trim level, but the biggest difference (apart from the blue one being a facelift model with some cosmetic changes) was the engine. The black 2011 Cruze had a 1.6 litre normally aspirated (i.e. not turbocharged) petrol engine, which supposedly developed around 122 bhp. The blue 2014 Cruze had a 1.7 litre turbocharged diesel engine, which developed slightly more power at 130 bhp. However, they were very, very different to drive.
Due to massively increased torque, the diesel felt much, much quicker off the line in spite of manufacturer's 0-60 mph figures which suggest there is not much between the two. At the time I owned the cars, they were driven by a syndicate of four of us, and we all enjoyed driving the diesel car much more with one exception: the heavy clutch, which made it much easier to stall in traffic.
Heavy clutches aside, however, another difference was fuel economy. All the time I owned the petrol 1.6, I averaged around 38 mpg, which I never felt was very impressive. However, the diesel 1.7 got over 52 mpg, which for a car which was doing around 17,000 miles a year as it was passed around the syndicate was rather more agreeable. It also helped that the petrol car's rather average emissions of 153 kg of CO2 per km were comprehensively trumped by the diesel's 119 kg of CO2 per km, which led to a huge £150 per year saving in road tax.
When I bought the diesel in 2015, everyone was still very much in love with fuel from the black pump, and those huge improvements in fuel economy and massive road tax savings were a blessing for all who had one. The main issues I seemed to have over the petrol were the fact that the oil needed changing much more regularly (the on board computer would flash this up itself) and also that unless the oil had been changed and the computer reset, the car would not self-clean its diesel particulate filter. This is essential for anyone who owns a Euro V diesel or newer, as not going onto the cleaning cycle regularly can mean flashing dashboard lights, the engine start/stop system not working and potentially forking out around £1000 for a new filter!
Particulate filter and oil change issues aside, however, I was quite happy to be driving around in something which effortlessly pulled along without having to rev high like a petrol, and got incredible fuel returns on the motorway (sometimes over 70 mpg on a long run). In fact, one of the people with whom I shared the driving of the car and I used to have competitions to see if we could get the best fuel economy on a longer run, which was a lot of fun!
Higher mileage motoring certainly can lean a driver towards some of Rudolf Diesel's finest fuel with which to power their car, but the choice really is not as simple as it sounds. A wake of motoring industry scandals and corresponding governmental prejudice against so called "oil-burners" since the news about Volkswagen cheating on emissions tests broke three years ago has meant that diesel is not flavour of the month any more, but for some it can still work out well.
Larger vehicles, such as people carriers and off roaders, almost always benefit from having good pulling power (or torque) to allow them to get efficiently off the mark, and traditionally diesels have been excellent for this. Before the widespread adoption of smaller capacity turbocharged engines during the mid 2010s, it was not really possible to get a vehicle of this type with a petrol engine returning anything like reasonable economy, and some manufacturers still only offer off roaders with diesel engines. Euro VI diesel engines, which are in all cars and vans registered in Britain after 1st September 2015, are compliant with the newer London Ultra Low Emission Zone legislation being phased in between 2019 and 2021, and those registered before 1st September 2018 do not suffer potential tax penalties over petrols. This may be about to change, however.
The way in which a car's emissions and economy figures are recorded for goverment statistics has been measured by a testing system called the New European Driving Cycle (or NEDC) for over 20 years now. This is incredibly unrealistic, and leads to massively over-optimistic fuel economy figures compared with real world driving for reasons upon which I will not elaborate now, but it does at least allow potential car purchasers to compare cars on a like for like basis. Due to the hugely unrealistic figures, however, a new system has been gradually introduced over the last year, and will become mandatory on 1st September 2018. This is called the WLTP (Worldwide Light [Vehicle] Testing Procedure), and is designed to produce more realistic figures for real world driving, whilst as well setting new standards for cars to match before going on sale. This is bad news for sales of new diesel cars, as due to the stringent protocols, many of them will fall foul of these standards without extensive modification.
With sales of diesel cars down by as much as 25% and a glut of used diesels hitting the market (particularly those registered before September 2015, which are not compliant with the new London UItra Low Emission Zone), it is not surprising that public opinion is swaying against getting any form of diesel car at all. Whilst I think that this is an over-reaction, and diesel can make really good sense for people who drive a high annual mileage (over 12-14,000 miles) and who have larger cars, my recommendation to most who drive a low to average amount of miles per year and have an average sized vehicle is to stick to petrol or go for an alternatively fuelled solution. Petrol/electric hybrids, whether they be plug-in or conventional, or fully electric cars are coming down in price a lot now, and can work out really well for those who live in a city or are able to regularly charge them on a private driveway.
As well as these alternative vehicles, it is worth bearing in mind that any petrol vehicle after 2006 is compliant with the London Ultra Low Emission Zone legislation, so particularly if you can find one with a small capacity turbocharged engine, this can work out really well for those used to diesel. The one in my 2017 Seat Toledo is a 1.0 litre three cylinder turbo which has very, very similar economy figures to the diesel Chevy (around 52 mpg), and none of the problems with the particulate filter or the chronic depreciation I experienced with it. This is a good stepping stone towards a hybrid or fully electric vehicle which we will all have to drive in the future. By 2040, the government hopes to ban sales of all fossil fuel cars, so this is no pipe dream, it is progress!
It is true that I certainly would consider a diesel which is compliant with the new WLTP standards in the future as my mileage seems to still be in the higher bracket, particularly if it had a good discount, but I have enjoyed the peppy performance and smoother refinement of my Toledo so much that it may not be enough to entice me back. Whilst those currently living away from London are not so affected by the anti-diesel prejudice, plans to introduce similar Ultra Low Emission Zones in Leeds and Birmingham suggest that it is only a matter of time before this becomes somewhat of a more level playing field. It only remains for me to say that if you would like me to source you a new vehicle which suits your needs, whether that be petrol or diesel, then I am more than happy to help.
