1st Nov 2011 by Admin
The number of cars now being powered by Diesel engines has increased to the stage that most vehicle manufacturers now offer at least one in their lineup. But what is the latest news on diesel and petrol motors and what should I be driving?
Research undertaken by Roy Morgan and published in the telegraph this month indicated that almost 1 in 5 private vehicles sold this year in Australia will be powered by a diesel. This is in contrast to less than 1 in 100 for hybrid vehicles.
Traditionally the argument for diesel has been focused on two things - better fuel economy and longer engine life. Both of these advantages mean that, over the life the engine, you will tend to save money with a diesel. However, the NRMA suggests, that this maybe a simplistic view and once you take into account the initial higher cost of the engine then the difference between Petrol and Diesel over four years is minimal.
The better fuel economy argument for diesel is still legitimate. Diesel engines definitely use less fuel than a petrol engine performing the same work. Petrol engines are typically 30 percent efficient while diesel engines can convert over 45 percent of the fuel energy into mechanical energy.
But as General Motor’s director of global advanced engineering stated, "There is certainly a convergence in efficiency levels between petrol and diesel engines, and while diesels will always maintain a slight advantage, the gap will continue to get smaller”. Petrol motors over the past decade, have introduced once-exotic efficiency enhancing hardware such as, direct fuel injection and turbochargers and while these technologies aren’t new, the incremental improvements in electronics and materials have pulled them into the mainstream. And there’s more on the way.
But don’t expect the diesel engine to lie down. "We’ll continue to see incremental improvements in diesel efficiency," says Marc Trahan, Audi’s North American director of quality and technology. Trahan says these smaller gains will come from hardware such as variable valve timing and independent cylinder combustion control, as well as improved after-treatment systems.
So let’s look at the historical problems that have held diesel engines back:
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