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Diesel vs Hybrid engines

By Sally Dominguez, 01 Jul 2015 Car Advice

Diesel vs Hybrid engines

Dreaming of a cleaner future or just want to save your pennies? We take a look into the diesel and hybrid debate.

With so many fuel-types available, it’s no surprise many are left blank-faced when buying a car.

As more options have entered the market, the choice on which fuel to run has become even more complicated. Today, there are more than three alternatives to petrol engines, including LPG, diesel and pure-electric. So, deciding which fuel choice is the most sustainable and efficient isn’t simple.

For the purpose of this article, the big debate sits between hybrid engines that combine fuel and electric boost, or fuel-sipping diesels.

Let’s take a look at how they compare…

Sales of diesel cars continue to rise rapidly in Australia due largely to the diesel engine’s reputation for fuel economy and the vast improvements car manufacturers have made to create quieter, cleaner and more efficient engines.

Diesel is particularly fuel-effective for larger SUVs used for towing or longer road trips. On the downside, even filtered diesel creates noxious emissions, and the production of diesel from crude oil creates significantly higher nitrous oxide (NO) emissions than petrol.

In Australia, a hybrid engine means the combination of either electric and petrol engines, or electric and diesel engines.

The hybrid’s electricity can come from a power point (known as a plug-in hybrid), but it can also be made entirely on-board using the conventional combustion engine as a generator. Both types of hybrid also use the braking motion in a car – called regenerative braking – to recharge the battery as you drive. The generated electricity powers the car at low speeds, sometimes assists with acceleration, and runs functions like lights and air conditioning.

The Toyota Prius has been the most popular hybrid in Australia for 14 years, but other manufacturers including Mitsubishi, Mercedes, Honda and Porsche now sell hybrids. When a car becomes available in petrol, diesel and hybrid variants, the diesel is usually several thousand dollars more than the petrol and the hybrid is more again. Maintenance costs for both engine types are also a fraction higher than petrol engines, but the real difference is in the fuel running costs.

Let’s talk average cents per kilometre (c/km) for fuel. The Mazda CX-5 SUV averages 11.39c/km using petrol, yet drops to 9.13c/km using diesel. The petrol Mitsubishi Outlander SUV clocks 11.54c/km, but the plug-in hybrid petrol-electric Outlander averages a miserly 6.86c/km. That’s a five-seat, medium-sized SUV chewing less fuel than some smaller cars and even less again if you plug the Outlander into solar panels.

There are terrific diesel engines on the Australian market that give you lots of power and bang for buck. A diesel-electric hybrid then, is a powerful, thrifty thing that lessens the negative impact of diesel fuel by defaulting to electricity whenever viable.

For example, Mercedes-Benz’s C300 BlueTEC Hybrid sedan is faster, uses 0.7L/100km less fuel and emits 13 per cent less CO2 than its diesel-only equivalent.

The major downside of diesel fuel is the environmental ramifications. If you want to steer entirely clear of diesel and still enjoy terrific fuel savings then a petrol-electric hybrid does the trick. The Toyota Prius, for example, has the same fuel consumption as the Mercedes hybrid, but emits five grams less CO2. So unless you’re really into accelerating quickly, it’s probably a better choice.

There’s plenty of options out there, you just need to do your research and check the figures. Save the environment, save your pockets or both… either way, hybrids are going to become more and more common in the market so keep a look out.

SHOWDOWN - diesel vs hybrid in litres/100km (claimed combined cycle)

The classic hatch:

Diesel: VW Golf 110 TDI Highline

Hybrid: Toyota Prius C

Prius uses 1.0L/100km less than Golf

Fuel-sipping SUV:

Diesel SUV: Mazda CX-5

Hybrid SUV: Mitsubishi Outlander PHEV

Hybrid Outlander uses 3.8L/100km less than CX5

Luxury performance sedan:

Diesel: BMW 3-series 320d

Hybrid: Porsche Panamera S E-hybrid

The Panamera hybrid uses 1.5L/100km less than the 3-Series