Last week Saturday, I went browsing for a new car. And as I left the house, my mother informed me in a serious tone that I should “try and get a diesel”. My mother is a wise woman – and I’ll explain why at the end of this post. But usually, I look at the diesel decision with some cynicism.
The Usual Arguments In Favour Of A Diesel Car
- Diesel cars hold their value better than petrol cars.
- Diesel cars are more efficient than petrol cars.
- Diesel is cheaper than petrol (in SA).
- Diesel servicing intervals are less frequent.
- Business Insider had some other reasons. But I think they’re mostly bogus. “The price premium over a gasoline car is lower than for a hybrid or electric car.” Honestly.
The Other Important Point
- Diesel cars are more expensive than petrol cars.
- Diesel services tend to be more expensive than petrol services.
So the question really is: at what point is the diesel car a better deal?
So I gave it some thought, and what we’re really trying to calculate is mileage. That is: at what point does the fuel efficiency saving become more valuable than the diesel premium. In an equation:
Total Cost of Vehicle = Purchase Price + Running Costs
Initially, the total cost of a petrol vehicle is less than that of a diesel (because running costs are 0 when you first buy your car). But over mileage, the total costs of the petrol vehicle catch up (Running Costspetrol > Running Costsdiesel).
I worked with three cars:
- The Polo Hatch 1.6 Comfortline
- The Ford Focus 2.0 Trend
- The Ford Ranger (the 2.5 XL vs the 2.2 MP XL – it was a bit more difficult to find a like-for-like with the more commercial-type vehicles)
And the mileage calculation
Break-even mileage = (Price Premium × 100) ÷ ([ed.fd] – [ep.fp])
- ed = fuel efficiency of diesel model
- fd = fuel price of diesel
- ep = fuel efficiency of petrol model
- fp = fuel price of petrol
And here are some answers:
Which says three things:
- If you upgrade your car at around the 60,000km mark, then you should be largely ambivalent about whether you go petrol or diesel.
- If you drive distance, you should go diesel.
- And if you want a 4×4, you don’t really have a choice.
In October 2013, President Mugabe gave in on his long-opposed position to mandatory ethanol blending of fuel. Zimbabwe’s parliament forced through legislation introducing 10% mandatory blending of unleaded petrol with the ethanol produced by a single company: Green Fuel. A quote from an official at Zimbabwe Energy Regulatory Authority:
“Anyone caught selling unleaded petrol [from October 2013 onwards] will face criminal prosecution.”
You’d think that the blending might have reduced the petrol price. It has not.
But more importantly, I recently had the opportunity to take my mother’s petrol car for a long distance spin. After the first 150 km, I was down to half of a 50 litre tank. That’s a fuel consumption of 17 litres per 100km, from a car that generally uses only 10.
Which makes it a pretty sweet deal for Green Fuel:
- a government-contracted monopoly on ethanol production;
- charging an unleaded price for blended fuel; and
- the fuel blend drives everyone’s consumption up.
My take-home message: when in Harare, go diesel or
go home stay home.