There’s been an explosion in the sale of diesel vehicles in Australian. When you add the sale of diesel cars to that of diesel SUVs the growth is immense: according to VFACTS data, diesel vehicle sales are up from about 92,000 in 2008 to more than 245,500 in 2016. That’s a huge increase in such a short space of time.
Why are so many people choosing diesel? Even more importantly, is diesel something you should consider?
The Good
Availability is Higher
The simple fact is that more vehicles today are offering diesel drivetrains. More choice means more sales. You can now get diesel engines in smaller city focused cars, rather than just large SUV’s and utes.
Diesel Grew Up
Diesel is no longer like grandad’s Massey Ferguson tractor. Modern diesel engines use hi-tech electronic injection control, common-rail piezo-electric injection systems and turbocharging for unprecedented performance and response.
It's More Fuel Efficient
Diesels deliver roughly 30 per cent better economy than equivalent petrol engines. They have more compression, so the expansion part of the cycle occurs over a greater range, delivering more useable power and better economy.
Diesel Beats Petrol at low Revs
Diesels make three or four times the torque of a petrol engine at about 2000rpm. Because these are the revs you normally drive at, diesels can scale hills effortlessly, are ideal for towing and just generally pull without complaint. Petrols need to rev higher and even then usually can’t match the peak torque of the diesel.
Diesel and Petrol Cost About the Same
Different factors affect the price of diesel and the price of petrol at the pump. Diesel is more closely linked to the state of the world economy. (When things are booming, demand for diesel increases, and so does the price.) But because diesel engines drink 30 per cent less fuel than petrols, you’re not really comparing apples and apples.
Diesels Cost More Up Front
It’s usually $2500-$5000 more for the diesel model. The engine is more sophisticated, and needs to be more robust, and is produced in lower volumes - hence the additional up-front cost. But this is not all bad news because…
You May Get Some of that Additional Cost Back When You Sell it
When you sell the car, some of the premium you paid up front (new) may be reflected in the value of the asset (used). In other words a used diesel Car A may be worth more than a used petrol Car A … all other variables being equal.
Petrol is Playing Catch-Up
The other big difference is where the fuel and air mix. In older petrol engines the fuel is squirted into the air just before it enters the combustion chamber. In diesels the fuel gets squirted directly into the combustion chamber at the last minute. This is called ‘direct injection’. Some petrol engines from the major european brands now feature direct injection technology - which has improved their performance and economy.
But It's Not All Benefits...
Diesel Isn't Always Available on Every Bowser
Petrol pumps out-number diesel pumps about eight to one - so, at an unfamiliar service station you'll need to keep your eyes peeled for the diesel bowser on your way in. It’s also dirtier, too, because diesel doesn’t evaporate like petrol does. You may smell like eau d’diesel after re-fuelling
The Exhaust Functionality Could Be a Problem
Diesels have particle filters in the exhaust to trap microscopic particles harmful to human health. Some highway running (say, every two weeks) is required for the filter to heat up sufficiently to burn off these injurious particles. (They call it ‘regeneration’.) If you don’t do that, the filter could clog and you’ll need a trip to the dealer to sort it out. So, if you do only short trips in the city, diesel might not be for you.