We don’t mean to confuse, but comparing petrol to diesel, and hybrid to EV, can give anyone a headline if the right figures are picked. So let’s dissect them properly, starting with a $27K Audi A1 Sportback 1.0-litre turbo three-cylinder petrol that consumes 4.2 litres per 100 kilometres on the combined-cycle fuel consumption test. Then a $38K Peugeot 308 Allure wagon that claims the same but feeds its 2.0-litre turbo four-cylinder with diesel.

Now, another headline: that same i3 could cost 50 per cent more to recharge than that same Prius.

These are the most fuel-efficient non-hybrids available for the least amount of coin.

Now for the yardstick, a $35K Prius that claims 3.4L/100km for the 1.8-litre petrol engine part of its electric motor hybrid powertrain. To halve that fuel score to 1.7L/100km, plus 0.134 kiloWatt hours per 100 kilometres, you’ll need a $50K Mitsubishi Outlander Plug-In Hybrid Electric Vehicle (PHEV). It has a big 9.8kWh battery that can – unlike the 1.3kWh-rated Toyota – drive 54km on electricity alone. Then a 2.0-litre petrol four-cylinder kicks in, ending the first half of 100km on 'free’ energy … although, nothing really is free, is it?

And finally, at under $70K there’s the BMW i3 with a 33kWh battery pack and without an internal combustion engine (ICE). At over three times the battery size of the Mitsu, the BMW packs almost six times the range, with a quoted 290km (but ‘usable’ 200km), while claiming a barely higher 0.136kWh/km due to its smaller body and lighter kerb weight.

Short of a twice-the-price Tesla Model S (with 455km) a BEV can’t yet, however, match the 600km-to-1000km range of an efficient ICE such as in Prius, A1 and 308.

Let’s look at the power costs of electric cars

To ensure the playing field is level, though, let’s take each cost not for a full ‘tank’ but per 100 kilometres, then per 15,000km. Over a rolling 12 months in New South Wales, premium unleaded (used for the fuel claims) has asked 149.5 cents per litre, versus 137.8c for diesel.

Electricity is trickier. A national average of 34c per kWh doesn’t take into account green energy or variable fluctuations. It’s our base, but we note that in Sydney current energy prices are more like 53c per kWh, plus 5.61c to tick green energy. And yet even the highest provider there tumbles to 14.42c per kWh (plus 5.61c again to go green) if you recharge after 8pm daily. This is how headlines can ‘correctly’ claim contrasting facts.

For every 100km, then, a Prius costs $5, a 308 $5.79 and A1 $6.28; and over 15,000km they ask $762, $868 and $942 respectively.

Using the national average electricity price, if an Outlander PHEV ran for half the 15,000km on electricity it would total $341.70, with the other half on unleaded at $190.62 for a $532.30 annual bill. A couple of hundred dollars saved over a Prius is not bad given this five-seat medium SUV costs only $15K more than that medium liftback; about the difference between a Camry and top-spec Outlander in petrol-only format, anyway.

To emphasise the fluctuations beyond 33c per kWh, though, let’s take the i3. At that charge it will ask $4.62 per 100km and $693.60 per 15,000km. At the highest charge above, 58.61c per kWh, the BMW soars to $7.97 per 100km and $1195 annually to be the costliest here.

From that same electricity provider, though, charging after 8pm suddenly cuts this – even with green energy ticked – to $2.72 per 100km and $408.61 annually, the cheapest here.

It gets better, because energy company AGL is charging a flat rate of $1 per day – $365 per year – for EV owners to recharge as much as they want over that period. Whether it be Outlander or i3 or a Tesla Model S or Model X, petrol and diesel can’t compete with that.

Nor do they have tricks up their sleeve like EVs do. Sure, snake oil salespeople have over the years promoted ‘miracle’ fuel devices that use magnets or ceramics to boost fuel or air flow, but they simply do not work to boost fuel economy.

Lower ongoing costs with free recharging for EVs

Meanwhile, given that EV sales are so low – 1124 were sold last year in a one-million-plus market – there is also not yet a high demand for public recharging infrastructure, so most of this rapidly growing network is currently free to use. In Sydney, BMW will allow you to recharge for free at Bondi Junction Westfield while you shop, while Tesla provides 400kWh of free energy credits annually via its class-leading Supercharger network nationally.

Other providers around Sydney, including a council carpark in the CBD, plus two shopping outlets each within a 5km radius, permit both priority parking and free recharging too.

High cost home recharge stations add plenty of dollars to your EV bill

A downside is that BMW also charges $1750 to install its 3.7kW home recharging kit dubbed i Wallbox Pure. Third-party EVSE Australia will provide a 22kW and 32-amp three-phase kit compatible with the new Renault Zoe, recharging it in just 2 hours and 40 minutes (versus 15hr at 3kW or 7hr 30min at 7kW/32A). It is priced from $1600 plus $900 installation, though, while Tesla throws a 16.5kW charger in for free, it costs $1000 to install.

Fewer moving parts means cheaper maintenance bills for EVs

And then it’s back to upsides. With fewer moving parts than an ICE, an electric car doesn’t require the usual oil and filter changes. Tesla’s three-year plan costs $2100 versus $3280 for a rival Mercedes-Benz E-Class diesel, and BMW’s i3 asks $950 over five years compared with $1395 for a similarly priced petrol X2 small SUV; while the Zoe needs just $693 over three years.

Batteries will, however, degrade over time, but Tesla and Toyota cover their units for eight years while Renault claims five-year coverage. Toyota confirmed that replacing its batteries costs $2000 to $3000 – important for hybrid Camry cabbies – and naturally that could be significantly more for packs of almost eight times the size in the Outlander’s case.

Conversely, battery prices are expected to tumble dramatically over the next eight years – forecasts indicate a fall from A$473 per kWh to A$158 per kWh by 2025. Buy a Model S 75D with a 75kWh battery pack today, and in eight years it could still have a raw (manufacturer- not public-cost, and plus labour) $11,850 replacement fee. Ouch!