The deal with diesel

When shopping for a truly fuel sipping vehicle in SA you have two choices, a hybrid or a diesel vehicle. I have performed calculations that show that a Prius is 22% cheaper to run than a diesel vehicle of similar price and weight and 20% cheaper to run than a petrol vehicle of similar price and weight.

I compared a BMW 120d, 2006 Prius and a Mercedes C180 BlueEFFICIENCY. The Prius beat them both. Of course I only looked at the running cost i.e. the cost for fuel over 1000km. I used the real world fuel consumption figures as tested by CAR magazine.I also did not compare performance. Even though the Prius was priced similar to the BMW and Mercedes, neither of the German cars had a navigation system or even leather seats. So the Prius is good value for money when it comes to features too.

But what's the deal with diesel anyway? It's well known that diesel vehicles use less fuel than an identical vehicle with a petrol engine. The reason is that diesel engines are more efficient than petrol engines, but diesel is also more energy dense. This means that one litre of diesel contains more energy than one litre of petrol. Petrol engines ignite the fuel by means of a spark while diesel fuel is ignited by compressing the fuel/air mixture untill it gets so hot that it ignites.

In the past diesel fueled vehicles have been known for being noisy, smelly, soot belching things only found on trucks and busses but  modern diesel engines are much cleaner and quieter. Emissions are still a problem though. The sale of diesel vehicles is prohibited in five US states due to emissions restrictions. Vehicle manufacturers have had some success with particulate filters, but even these measures are insufficient in light of newer more stricter emission laws. For many South African drivers having a diesel vehicle makes perfect sense, but we must remember our ultimate long term goal:


To stop using oil altogether


If we keep driving diesel vehicles we'll use less oil, but never get off it completely. This is where I believe hybrids and especially plug-in hybrids are the perfect bridge from oil fueled vehicles to electric cars. Hybrids and plug-in hybrids are a way to wean us off oil and onto electricity. Hybrids also allow manufacturers to mature the motors and batteries in the real world before placing them in electric-only vehicles. With Prius we can enjoy the benefits of petrol and electric propulsion with non of the drawbacks of using only one or the other.

I believe that eventually we'll leave diesels, hybrids and even plug-in hybrids behind and refill our cars using electricity from non-CO2 emitting sources. Batteries will eventually get so good that you'll be able to recharge them in minutes and drive hundreds of kilometres between charges.

It may all happen sooner than you think.

Posted 11 August 2009

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