"Diesel fuel is too expensive"

Why is Diesel fuel more expensive than Unleaded.
(Written 10 Jan 2005)

I am becoming increasingly annoyed by the price of Diesel fuel in Western Australia. On average it seems to be about 12 cents per litre more expensive than Unleaded fuel. Why is it so expensive?

Many of us are trying to lower the running costs of our vehicles by purchasing Diesel powered cars. Typically, Diesel cars and 4WD's consume 20-25% less fuel than their petrol powered versions. But with the price of Diesel being on average 10% more, then the real running cost improvement is only 10-15%.  And keep in mind that typically, the modern turbo-diesel powered cars are more expensive to buy, sometimes up to $10000 more, and so with such a small net reduction in running cost, it is possible that the owner will never see a saving over the lifetime of the vehicle. 

*** Update 10 Dec 2008: Today, Unleaded is as low as 99c/L, and Diesel is as much as $1.41/L, that's 42c/L more expensive, or 42% more! So assuming that Diesel vehicles consume 20-25% less fuel, currently they cost 21-22% MORE to run. That's not a very nice way to reward us diesel drivers for doing the right thing by the environment! This is ridiculous! I think it's about time the goverment stepped in to make policies to ensure that the oil companies can make diesel more affordable, be it by regulating sell prices, setting up more competition, or by lowering excises & taxes.

Why is Diesel becoming so popular? In years gone by, Diesel vehicles were noisy, sluggish, and bellowed black smoke, making them unpopular with their owners, and other road users alike. The modern turbo-diesel powered vehicles incorporate computer controlled engine management systems, more advanced fuel injectors (including common rail direct injection), and the fuel itself is cleaner as the government regulated to almost eliminate the sulphur content. These modern diesels often fool their drivers, who enjoy driving them blissfully unaware that their are even in a diesel vehicle. So, if you can drive a vehicle that feels like a Petrol powered vehicle, but enjoy a fuel saving, then why wouldn't you. Keep in mind that diesel vehicles typicall produce more torque than their petrol engined counterparts, making them more suitable for towing too.

What about the environment? Combustion of Diesel fuel emits less harmful gasses into the air than Petrol. Even the older diesel engines that often emit some black smoke are probably less damaging, as a lot of the "smoke" is soot particles (giving it the black appearance) and carbon dioxide, which is arguably less dangerous than the odourless clear toxin "carbon monoxide", which is emitted in larger quantities by Petrol combustion.

And maintenance? Diesel engines tend to last longer and be more reliable than Petrol motors for several reasons, including... 1) the combustion temperature is about 200 degrees C lower, 2) there are less critical components (no spark plugs, coils, high tension leads etc), 3) the construction of the motor is stronger to cope with higher compression ratios etc, 4) maximum torque is developed at much lower RPM as so the engines do not need to be revved as high.

So, now that we know why diesel powered vehicles is becoming so popular, why are we (us Diesel drivers) being disadvantaged with higher fuel prices? If we choose to spend more on a vehicle, to produce less harmful exhaust gasses, and consume less fuel, why are we not able to enjoy the full savings, due to higher fuel prices?

Unleaded fuel requires much more refining to produce than Diesel, after all, diesel is much closer to crude oil. Some say that diesel is almost the "waist product" of Unleaded fuel refining. This may not be so true now-a-days, as most companies are now producing much cleaner burning diesel, which I assume does require more refining, but I don't think as much as Unleaded. So, it should be cheaper, right? Wrong. I am not sure why this is the case, but I intend to find out as I do more research. Is it the oil companies, or is it our Government? And it seems the problem is worse here in my state (Western Australia), perhaps due to the mining boom in the far north. But shouldn' this mean greater supply and LOWER prices, rather than higher prices?

Watch this space for more info!

 These pages were last updated on 10 Dec 2008.