I can still remember when, not that long ago, diesel engines were considered smelly, dirty, noisy and underpowered lumps of metal. They were basically used in medium and heavy duty applications like buses, trucks or vans and the few cars that had them were slow and in general something to be avoided. Fast forward to 2009 and you can see them everywhere. Some cars, like the Citroën C6 or the Peugeot 407 Coupé are only sold with diesel engines.
Not only diesel cars seem to be the norm nowadays, but they have come a long way indeed from the early, and not so early, days. They have improved notably in the noise, vibrations and harshness department and they are ever increasing performance while reducing fuel consumption at the same time. Is there room for petrol engines at all these days?
I've always been a petrol defender. I've always thought that diesels were more suited to tractors and that anyone that bought a diesel was a bit greedy and not interested in cars. Certainly in some cases, like for instance people who do very high mileage, diesels do make a lot of sense and the savings are certainly noticeable. There are other cases though, in which people act like sheep. I have for instance never understood city cars with diesel engines under the bonnet. They are far more expensive than their petrol counterparts and the usually short distances driven by this sort of cars cannot compensate the price difference.
At the same time petrol engines have come a long way too. The latest technology includes direct fuel injection, turbocharging and downsizing. They have reduced fuel consumption and emissions greatly. Indisputably petrol engines are much more refined and smooth than diesels, even modern common rail units. You can try this by starting a petrol powered car and diesel powered car with the door open and then letting them idle. There's really no contest here. On the move the difference is much smaller, and here the advancements made by diesels are really clear. At high revs petrol beats diesel again, the noise made by petrol engines is much nicer.
And yet in some situations you just can't argue with diesels. In a recent 350km journey I did our BMW 118d recorded 7l/100km cruising at speeds between 160km/h and 180km/h about 90% of the trip. Even if you push hard you'll still struggle to get over 10l/100km. I have also had the opportunity recently to drive a brand new Lancia Delta T-Jet powered by a modern 1.4 litre turbocharged four cylinder engine. If you are careful with the throttle you can get relatively close to the BMW's figures, an average of 7 to 8L/100km is possible, but as soon as you start driving like an Italian numbers grow exponentially. 15L/100km aren't out of reach at all. So it doesn't look like you'll be buying a petrol for economy any time soon.
Despite all I still can't get to love diesels. I've driven one now for 1 and a half years and it's been brilliant, fast and frugal. It's not perfect though, there's still a bit of turbo lag and it isn't as refined as a good petrol motor but so far very good indeed. But I don't want it. Aside from the problems already mentioned, it makes me feel cold like if it was an appliance. When you are in your favourite mountain road enjoying the brilliant drive of your car the diesel engine is a big let down, it detracts much from the experience. I'm sure this is accentuated by the brilliant driving abilities of the little bimmer, and I wonder what would happen if the diesel was in the Delta and the petrol in the 1 series.
Then there are case in which a diesel engine simply has no place. These include cars with sporting pretensions like hot hatches and more than anywhere sportscars. Also some brands like Alfa Romeo or Jaguar, simply shouldn't offer a diesel at all, because those cars should be viewed as pure driver's cars and no driver's car should be saddled with a diesel engine because it's simply a sacrilege and there's no argument to be had here. Furthermore they have an heritage, expertise and aural pleasure that should never ignored. Of course for a bit of weekend fun petrol still reigns supreme.
However in the real world diesels do make a lot of sense, especially as soon as you are off the city and on to roads and motorways. The arguments for diesel are very strong and other than the romantic view it's difficult to make a case for an everyday petrol powered car. Heart says petrol, but head says diesel. What's it going to be?