Petrol vs Diesel vs Hybrid vs Electric: These are the ins and outs of each vehicle type

IOL News

2 days ago

Electric vehicles remain an uncommon sight in South Africa, but hybrids are gaining in popularity.
Image: Newspress
With the advent of hybrid and electric powertrains, buying a vehicle has become a far more complicated equation.
Do I pay more for something with an electric motor, and save on fuel costs down the line?
It's still not an easy question to answer as there are many variables involved with each specific model range, but it helps to gain an understanding of the various propulsion systems and where they fare best. Internal combustion engines: the traditional way
Petrol and diesel engines, commonly labelled as internal combustion (ICE), have powered cars since the beginning, and they remain the mainstay of the motor industry, as in most instances they're still more affordable than hybrids and electric vehicles (EVs).
A petrol engine is typically the least efficient propulsion type. Although they can be relatively economical at constant highway speeds in higher gears, they are generally thirsty in town driving scenarios.
Stop-start driving, where the lower gears are used, is when a petrol engine is at its least efficient because the engine needs to attain high revs in order to move the car off the mark, which takes a great deal more energy than cruising at freeway speeds at lower revs.
Diesel engines have a more efficient combustion process that extracts more energy from the fuel, allowing them to produce more power and torque at lower revs, but because they require more sophisticated technology and often bigger engine sizes in order to achieve the same outputs as their petrol equivalents, they tend to be more expensive to purchase.
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The Kia Seltos is one of the few affordable passenger cars still available with a diesel engine.
Image: Supplied
For instance, a Kia Seltos 1.5 CRDI LX turbodiesel costs R29,000 more than its normally petrol equivalent, which has the same power output. But the diesel offers better fuel consumption, at a claimed 5.2 litres per 100km versus 6.3 for the petrol, and more torque (250Nm versus 144Nm), which is good for low-rev cruising and hill climbing.
Diesels have become less common in the passenger vehicle market, however, as their higher levels of particulate matter make it harder for them to meet global emissions standards.
Understanding hybrid powertrains and their many variations
Hybrids often claim to offer the best of both worlds. This powertrain type is typically abbreviated to HEV, which stands for hybrid electric vehicle. With an extra dash of romance, Fiat likes to use the 'Ibrida' title, which means hybrid in Italian. Is there anything that doesn't sound appealing in Italian?
But in fairness, not all hybrids are born equal, and quite frankly, not all of them truly deserve that title.
So-called 'mild hybrids' are often a point of contention.
Operating a 48-volt electrical system, rather than the 12-volt set-up typically found in regular ICE cars, mild-hybrids replace the starter motor and alternator with an electric motor and small battery.
Although the e-motor provides a small performance boost, the fuel economy gains tend to be negligible at best as these systems more often than not do not propel the car on electric power alone.
They do however make a small difference by using recuperated energy to power some of the car's electrical components, and even the air conditioning in some cases, easing the strain on the engine.
Yet regular 'self-charging' hybrid systems like the one found in South Africa's best-selling HEV, the Toyota Corolla Cross, often hit a sweet spot for consumers.
The Corolla Cross is Mzansi's most popular hybrid.
Image: Supplied
Like diesel engines, they tend to cost more than their petrol counterparts, for the benefit of better fuel consumption, but it's important to understand the scenarios in which each engine type operates at its most efficient.
Hybrids typically pair a petrol engine with one or more electric motors, which power the car together or alone depending on the circumstances.
For instance, the Corolla Cross 1.8 HEV has a 53kW electric motor that can power the vehicle alone at lower speeds, in lower gears, thus taking the strain off of the petrol motor when it's at its least efficient.
Toyota claims a combined fuel consumption figure of 4.3 l/100km for the hybrid, in ideal test laboratory conditions, versus 6.8 for the regular 1.8-litre petrol model, which is R38,200 cheaper in XS trim. But that doesn't tell the full story.
In our month-long road test of the Corolla Cross HEV, our test unit consumed a shade over 6.0 litres per 100km in town driving scenarios and 5.6 l/100km on a 1200km highway trip.
Notice the small gap between those figures?
Normally an SUV of this size would consume well over 9.0 l/100km in town. But the highway figure, while still impressive, is not significantly better than what a conventional ICE engine would achieve. That's because the lack of braking at constant highway speeds results in limited energy recuperation, meaning the e-motor can't do as much of the work as it would in town.
The bottom line is that hybrid vehicles will hit the sweetest spot for those who do most of their driving in urban environments, while a diesel engine would still be better suited to those doing a great deal of longer-distance driving. Sadly, the Corolla Cross is not offered with a diesel. Plug-in hybrids: having your cake and eating it?
The city driving advantage of a hybrid is amplified further when it comes to the plug-in type, otherwise known as a PHEV.
These work much like the aforementioned regular hybrids, but have much bigger batteries that typically allow these vehicles to cover anything from 50km to 100km on electric power alone. In fact Volvo's upcoming Ultra PHEV models promise electric coverage of up to 200km.
Volvo is a big player in the PHEV space.
Image: Supplied
Keep in mind that the 'claimed' range figures will differ greatly, depending on the mixture of urban and freeway driving, and of course, your driving style.
But theoretically, and provided that you charge your PHEV on a regular basis, you could do your daily commuting on electric power alone, while the petrol engine waits in the wings for that odd long-distance trip to the coast.
It is a bit like having your cake and eating it, depending on what your needs are.
A PHEV could actually work to your detriment if you do a significant amount of long-distance driving. Because they have heavy batteries to lug around, once the battery power has been depleted, these vehicles are often less efficient than regular ICE vehicles at highway speeds.
Bottom line: If you own a trendy coffee shop downtown - assuming you're not already cruising around on a bicycle with a basket - a PHEV could make a great deal of sense. But if you're the Chief Rep from Pep, best you stick to that diesel.
The other thing to consider is that PHEVs are more expensive than conventional hybrids and ICE vehicles.
The least costly option at present is the BYD Sealion, starting at R639,900, but most other options are positioned north of R1 million. Thankfully there is a slew of new Chinese contenders heading to South Africa this year, which will likely make PHEV ownership more accessible.
Nonetheless, a PHEV is by default a performance model, because its ICE and electric motors both need to power the vehicle individually at higher speeds, so unlike a conventional hybrid, smaller motors are out of the question.
The ins and outs of an electric car
Fully electric cars, commonly referred to as EVs, are solely powered by electric motors and have far bigger batteries than PHEVs and HEVs, sometimes with capacities exceeding 80 kWh.
Compared to ICE vehicles, EVs offer minimal running costs, with Nedbank estimating an at-home charging cost of around R200 for a full battery.
The relative simplicity of e-motors also makes these vehicles cheaper to maintain. But as with PHEVs, electric cars are really expensive to buy.
BYD ATTO 3 crossover.
Image: Supplied
The least costly EV option in 2025 is the Dayun S5, at R399,900, which in fairness is best suited to city driving, while the family sized BYD Atto 3 family-sized SUV is perhaps the most viable real-world option at R768,000, not forgetting the Polo-sized BYD Dolphin at R539,900.
While some of the smaller EVs offer claimed range figures of around 300km between charges, most products nowadays claim to cover 400km or more, but keep in mind that real-world range figures will differ radically depending on your driving style and driving scenario.
When it comes to efficiency, an EV is very much the exact opposite of an ICE vehicle as the former is far more efficient in urban driving scenarios. This is because stop-start driving maximises energy recuperation from braking, which helps extend your range bit-by-bit.
Quite telling was a recent real-world range test conducted by AutoTrader at the Gerotek high-speed oval.
At a constant speed of 117km/h, the BMW iX1 took 238km to deplete its battery from 90% to 10%, emulating real-world battery usage. The BMW's claimed range figure is 440km on a full battery. At similar speeds the Volvo XC40 Recharge covered 214km/h and the Mercedes EQA 250 managed 254km/h, versus their claimed range figures of 460km and 402km.
Keep this in mind when planning that trip to Durban. In fairness, companies such as GridCars and Charge are constantly expanding the country's rural charging network and in time, long-distance driving will become less of an obstacle to EV ownership.
For now, purchase price remains the biggest hurdle to electric motoring, and until the government follows the lead of other countries by offering purchase incentives, or even equalising the import duties with ICE vehicles, EVs will remain a small niche in this country.
Home charging, with South Africa's patchy electricity grid, also remains an obstacle for potential consumers, although ultimately, reaping the environmental advantages of EV ownership should ideally mean having a solar infrastructure at home. Because what's the point of a coal-powered car?
Assess your needs
Although this was by no means a thorough technical explanation of the differences between ICE, hybrid and electric vehicles - such a feature could take up a novel - we do hope that it provides a bit of insight into the ins and outs of each particular propulsion type.
Remember to shop around, assess your needs and take the 'official' fuel consumption figures and range estimates provided by manufacturers, with a pinch of salt.
IOL