Electric Vehicle versus petrol power: is a BEV really that much cheaper to run?
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Electric Vehicles (EVs) are still a relatively new phenomenon in the New Zealand new-vehicle market. But the big headline about plug-in cars seems to be ultra-low running cost.
EVs are cheap to “fuel”; even the biggest electro-sceptics would probably agree with that. How cheap? Well, how long is that piece of string again?
What we really need to do is compare the petrol/charging costs and efficiency of a Battery Electric Vehicle (BEV, or pure-electric) with its Internal Combustion Engine (ICE) equivalent. And that’s not easy to do, because so many BEVs are standalone models.
You could compare the Mercedes-Benz EQC BEV to the GLC, but they’re not exactly the same. Or a Jaguar I-Pace BEV to the F-Pace, but again – not a completely obvious comparison. A Mazda MX-30 is roughly equivalent to a CX-30, but also a very different proposition. There’s no Nissan petrol hatch to line up against the latest Leaf, either.
We’re getting much warmer with the Hyundai Kona Electric, which has closely related Internal Combustion Engine (ICE) siblings. Or even the Mini Electric, which is a genuine alternative to the sportier Mini hatch models.
But here’s an ideal match: the MG ZS EV and its sister ICE model, the ZST turbo-petrol. They’re both based on the same compact SUV architecture, with similar power (105kW for the EV, 110kW for the ZST) and both in top-line Essence specification.
The ZS EV (above) is also NZ’s cheapest BEV and in demand on the back of the Government’s $8625 Clean Car Discount. With that accounted for, it’s just $40,365 – inexpensive for a BEV, although still $6375 more than the $33,990 ZST (below).
One of the tricky things to get your head around is that we express efficiency in different terms for petrol versus BEV. We’re used to talking “litres per 100km” for ICE cars; it’s 7.3 for the ZST.
With BEVs it’s usually range, probably because recharging time is such a big thing; the ZS EV offers 263km from its 44.5kWh battery. But you can express that as something closer to l/100km, which in the ZS EV’s case is 18.6kWh per 100km.
Taking an average fuel price of $2.40 per litre, the ZST will cost $17.50 in petrol to drive 100km. How does the ZS EV compare? That’s a question that requires more than one answer.
Charging at home
The Government’s RightCar website assumes an electricity price of 15 cents per kWh to charge a BEV at home – lower than the national average for power generally, but then BEVs are often plugged in at overnight rates.
Based on that figure, it costs about $2.80 to get 18.6kWh of charge into the ZS EV to drive 100km. Which seems laughably cheap.
But if you are charging at home, most experts would recommend an AC wallbox-style unit, for convenience, extra speed (up to six times faster, meaning you can charge from flat overnight) and safety. That could cost several thousand dollars, so you need to factor it into the BEV purchase price. It’s optional of course, but good way to spend some of that rebate?
Charging at public DC stations
Public DC stations are plentiful in NZ and the fastest way to charge a BEV: most are 50kW (per hour), but some of the newer machines are much more powerful – up to 300kW, for the BEVs that allow it.
Let’s keep it simple and assume you’re taking maximum advantage of a “grazing” style of charging, based on a consistent 50kW speed (yes, we know it’s not quite that simple). ChargeNet is the biggest DC fast-charge provider in NZ: its product is priced at 25 cents for every kWh you draw and you pay 25 cents for every minute you’re parked there.
So a ballpark equation is $4.65 for 18.6kWh and another $5.60 for the 20-plus minutes you’re parked there. Total: $10.25 for 100km.
Several power companies offer free DC fast charging in Auckland and Waikato at the moment, and that’s a nice bonus. But it can’t last forever and we wouldn’t recommend purchasing a BEV on the expectation of free power.
Overall then, charge the MG ZS EV at home and it’ll cost about 80 per cent less to power than the turbo-petrol ZST. You’re saving about $15 per 100km, which sounds good – but bear in mind it’ll take you in excess of 40,000km to recover the extra money you spent on the EV over the petrol ZST.
Worst case scenario is that you charge exclusively at paid public DC stations. The EV would still be 60 per cent cheaper, but that knocks your saving back to about $7 per 100km. So you’re looking at 90,000km-plus to break even.
But like we said, nobody would really do that. DC stations are more for top-ups and longer journeys, where you need to charge as quickly as possible and then move on.
The elephant in the room
EVs are exempt from Road User Charges until at least 2024. What happens after that is anybody’s guess.
But for the sake of argument, if you add the RUC of $76 per 1000km (or $7.60 per 100km for our DRIVEN maths) into the equation, that erodes the savings from our home-charge scenario to around 55 per cent.
What’s the verdict?
Clearly, if you’re buying a new EV based solely on its potential to save you money, the extra capital cost of mainstream BEVs like the ZS is still a drag on the considerable running-cost savings. Although you still come out ahead after a typical ownership period of, say, three years.
It’s less of problem with premium product from the likes of Audi, BMW, Jaguar and Mercedes-Benz, because there’s more price parity between BEV and ICE. But buyers of $100k-plus vehicles are less likely to be worried about it, too.
It’s also less of a problem for used-import BEVs (which still get a $3450 rebate if they’re being registered for the first time), because it’s entirely possible to find the likes of a Nissan Leaf at a comparable purchase price to an equivalent ICE like a Toyota Corolla.
You’ll note we haven’t really included servicing costs, partly to keep it simple and partly because that’s not always a known quantity. Perceived wisdom is that BEVs are much cheaper in that regard, but the schedules and pricing for new vehicles are not that far apart.
An MG NZ spokesperson confirms that the total servicing cost difference is “negligible” between the ZS EV and ZST: “in the vicinity of $50-80” over five years, despite the intervals for the EV being twice as long at 20,000km. The longer-term advantage will come in consumables like lower brake and tyre wear – and less time spent at the dealership of course.
But overall you could argue the current obsession with cheap running is also partly an indication of the immaturity of NZ’s BEV market. Plug-in vehicles are the future regardless and while we can count on their purchase price coming down – we can also count on buyers switching on to the driveability and environmental advantages of BEVs as they become more a part of everyday motoring life.
If saving money was the number one priority, we’d all just take the bus.
MG ZS EV VERSUS ICE
Pros: Huge $8625 Government rebate, 80 per cheaper to ‘fuel’ when charged at home, DC fast-charge option for long-distance driving
Cons: Still $6375 more expensive to buy (40,000km to break even), DC fast-charging three times the cost of doing it at home, no cheaper to service over five years