Hybrid vs diesel: Which is cheaper?

While diesel passenger cars are now rarer than they were five to 10 years ago, they’re still around with the likes of Kia, Mazda, and Renault still registering diesel cars.

The perception of diesels have changed, especially in Europe, with increasing scrutiny of their impact on air pollution and health. Diesels passenger cars are much cleaner than they used to be, but they’re still not as clean as gasoline ones (especially when it comes to oxides of nitrogen) – let alone hybrids or electrics.

Not many people will care about that – even if it is very important and Singa pore’s air quality sucks – but let’s put those issues aside and concentrate on our wallets for now.

We’ve been wanting to compare diesels and hybrids once again, but only one car here is offered with both drivetrains: The Kia Sorento. It launched as a diesel in 2020, and Kia has just introduced a ne w hybrid variant, which we’ve test driven and found very impressive.

To that end, we went to town with our spreadsheet (see below) to see if the Kia Sorento Hybrid or Kia Sorento Diesel is more cost effective. The short answer is, it’s the Hybrid. The ‘long’ answer is also, it’s the Hybrid.

Diesels have to pay more road tax than normal passenger cars, but the old wisdom is that over a longer distance they recoup that through cheaper fuel (diesel is subsidised by the government). Compare a diesel to a normal gasoline car, and that’s almost always the case.

But compared to a hybrid, the diesel loses out on all fronts. Why? Because the government recently reduced the Road Tax for hybrid electric vehicles – the Sorento Hybrid demands only S$739/year in road tax, compared to almost triple $2,052 for the diesel. And with the Hybrid being more efficient, there is no logical situation where the costs even out.

As you see in the chart below, even if you drive 100,000km a year – and assuming your butt doesn’t fall off or you don’t go insane – the diesel doesn’t break even. The LTA’s useful statistic here is that the average Singaporean driver covers around 18,000km per annum – so even if you go more than five times the national average you’ll still pay more to run the diesel.

Now here’s the but…

There are some caveats though: Compared to a gasoline-only car, the diesel would be cheaper. A large SUV like this powered by a 2.0-litre or 2.4-litre gasoline engine would consume at least eight or nine litres per 100km.

Also we calculated running costs with only fuel and road tax in mind – we didn’t account for consumables including tyres and AdBlue, which diesels need to top up every so often. It’s an added cost, but not a huge one – around S$20 per 10-15,000km.

The but-but is that both Hybrid and Diesel are more efficient than a normal gasoline car anyway, and offer regular drivers an alternative to painful gasoline-only prices at the pump.

Kia Sorento Hybrid vs Diesel yearly running costs at 5k, 10k, 30k, 50k and 100k km

This article was first published in CarBuyer.