EV vs petrol vs hybrid: the honest hatchback maths for Australia

Something happened quietly in Australian showrooms this year: the electric hatchback price premium disappeared. An electric BYD Dolphin Essential is $33,792 drive-away. A petrol Mazda3 G20 Pure is $32,990. A Corolla hybrid hatch lands around $35,500. For the first time, “should I buy an EV?” isn’t about recovering a big premium — the difference is about $800.

So we built the model most comparisons skip: a real Australian household simulated hour by hour for a full year, real-world (not brochure) fuel and electricity figures for every car, and every option priced — petrol, hybrid, EV, EV with solar, EV with solar and a battery, even fully off-grid. This is the hatchback edition; the mid-size SUV edition is next, and its answer is different.

The short answer

For an average driver (12,000 km a year), the electric Dolphin costs about $680 a year less to run than the petrol Mazda3 — charging and servicing included. That wipes out the $800 price difference in about a year. On one of the cheap overnight EV power plans now offered by several big retailers, the saving grows to about $1,090 a year. The Corolla hybrid also beats petrol — but the EV is cheaper to buy and cheaper to run than the hybrid, so in this class it wins on both ends.

Option (average driver)	Pays for itself in	Extra cost vs petrol	Saving vs petrol
Corolla hybrid	~4 years	~$2,500	~$620/yr
Dolphin EV (our pick)	about a year	~$800	~$680/yr
EV + solar	~3.5 years	~$7,500	~$2,070/yr
EV + solar + battery	~6 years	~$18,000	~$3,240/yr
EV, fully off-grid	Never — see below	~$50,800	~$4,180/yr

These numbers are for when you’re buying a car anyway. Already own one that works? Keep it — see below.

Different cars, different kilometres? Our free hybrid vs petrol calculator runs these same real-world figures on your own numbers — petrol, hybrid, plug-in hybrid and EV side by side, every field editable, no sign-up.

One more thing to read the table right: the solar, battery and off-grid rows price those systems as new purchases made alongside the EV — the whole package, bought together. Already have solar on the roof? That money is spent — leave it out of the EV’s sums. Your EV just charges on cheap daytime power from day one, so your deal is better than the bare-EV row shows. The table answers “what should I buy?”, not “what’s my existing kit worth?”

Light drivers (8,000 km a year) still come out ahead — about $490 a year, paid back inside two years. Heavy drivers (20,000 km a year) save about $1,200 a year, even after buying a wall charger. Part of that is servicing: petrol schedules are “12 months or 15,000 km, whichever comes first”, so at 20,000 km you’re paying for a third more services. The EV’s 20,000 km interval stays one service a year.

Brochure figures vs the real world

Here’s the part most comparisons fudge: manufacturer consumption claims. The Australian Automobile Association drives cars on real roads and measures what they actually use — for EVs, measured at the power point, so charging losses are included. We used their numbers, not the brochures:

Car	Claimed	Real world	Uses more than claimed
BYD Dolphin (electric)	14.2 kWh/100km	17.7 kWh/100km	+24%
Mazda3 (petrol)	5.9 L/100km	6.1 L/100km	+3%
Corolla hybrid	4.0 L/100km	~4.2 L/100km	~+5%

Don’t compare the EV’s number with the petrol numbers — they’re different units. The last column is the comparison.

The Dolphin’s claim is optimistic by a quarter — a real cost of about $150 a year, and we’ve charged the EV for it. The Mazda3 turns out to be one of the honest ones, and Toyota’s hybrid savings genuinely held up on the road. It cuts both ways, though: across the same testing, three-quarters of petrol cars used more than advertised (some by over 30%) — while the Tesla Model Y actually beat its claim. We model on measured numbers so none of that guesswork ends up in your decision. And note: our petrol baseline being honest stacks the deck against the EV — which still wins.

Add solar and the winnings roughly double

The bare EV pays for itself fastest. But “fastest payback” and “most money” are different questions. Over ten years, in today’s dollars:

• EV alone: about $4,800 better off than petrol
• EV + solar: about $9,400 better off — roughly double
• EV + solar + battery: about $7,900 at ten years, but around $15,900 at fifteen — it overtakes everything if you stay put long enough

(Quick maths note: ten years of $680 looks like $6,800, not $4,800. We count future dollars as worth a bit less than today’s — that’s the fair way to compare a big purchase now against savings that arrive slowly.)

The pattern: solar is a moneymaker stacked on a moneymaker. The battery is the marginal piece — on a standard flat-rate power plan it loses money over ten years and only edges ahead past year twelve. On a plan that charges different rates at different times of day, a battery earns more than our flat-rate model shows — but that’s a plan-by-plan sum, not a blanket promise. In 2026, buy a battery for backup first; the economics are the improving bonus.

And fully off-grid? Even counting the fixed daily supply charge you’d never pay again (the fee just for being connected), it’s around $17,000 worse than staying connected with the same solar and battery — before the battery bank replacement due around year ten. We tell you when not to spend: this is one of those times.

Charge it right — the trick most people miss

Two free moves turn a good EV deal into a great one:

• Cheap overnight EV plans. Several big retailers now sell plans with overnight EV charging around 4.5–8c/kWh — versus a typical 36c/kWh flat rate. That one change roughly halves your charging bill. Compare plans on the government’s Energy Made Easy site.
• The Solar Sharer window. Eligible households in NSW, south-east QLD and SA can opt into three hours of free midday power — if your car is home at lunchtime, that’s free driving. We’ve covered how it works and the catches.

One myth worth killing: at 12,000 km a year, a Dolphin needs about 6 kWh a day — three to four hours overnight from an ordinary power point. Most average drivers don’t need a $1,800 wall charger at all. We only priced one in for the heavy-driver case.

The road-trip reality check

Our model assumes you charge at home, because that’s what hatchback life mostly looks like. Long trips are the honest exception, twice over:

• Cost. Public fast charging runs about 40–65c/kWh (up to ~85c/kWh on some ultra-rapid chargers) — one and a half to two times your home rate, and five to ten times a cheap overnight EV rate. Holiday kilometres cost more than commuting kilometres.
• Queues. The charging network is growing, but so are EV sales — and the crunch lands exactly when everyone travels at once, on the Easter and Christmas runs between capitals. A hatchback doing the coast trip plans around chargers in a way no petrol driver thinks about.

If your driving is mostly around town with the odd getaway, this barely dents the maths. If you regularly haul long distances, factor it in properly — that’s a genuine argument for the hybrid, which asks for no infrastructure at all. A dedicated road-trip piece is coming; the short version is it’s a planning problem, not a dealbreaker.

Security comes before savings

In professional energy management there’s a pecking order we’ll unpack in a coming piece: keep the energy flowing first, cut the cost second, green it third. Almost everything above lives on the cost step. One thought from the base step before you decide: going all-electric puts your whole household — transport included — on a single supply, the grid. A petrol household in a blackout can still drive.

That’s the honest remaining argument for the hybrid: it runs on a fuel network the grid can’t take down. Two-car households can hedge naturally — one EV for the cheap kilometres, one petrol or hybrid as the backup fuel. Solar and a battery buy back some of the security you gave up by electrifying — which is the fairer way to judge the battery’s so-so economics: it’s a backup purchase that also pays part of its way. And off-grid, which never stacks up on cost, is really a pure security purchase — price it as one. For most households the grid is reliable enough that cost decides it; if you’re rural or outage-prone, give this step real weight.

Already own a car that works? Keep it

Everything above compares new car vs new car — the decision you face when your old car is due for replacement anyway. Selling a working five-year-old petrol hatch to switch early is a different sum. Even selling privately at a fair price (RedBook puts a 2021 Mazda3 at $17,000–20,400), you’re putting in roughly $15,000 to save about $680 a year — a payback measured in decades. Trade it in at a dealer and it’s worse. Same rule we apply to working air conditioners and hot water systems: run it to the end of its life, then buy the efficient thing. The EV wins at replacement time; it rarely justifies retiring a healthy car early.

The fine print that actually matters

• Employed? You might save thousands more — until 31 March 2027. If you can get the car through your salary (a “novated lease” — your employer pays for it from your pre-tax income), the current tax exemption makes an EV worth thousands a year on top of everything above. It’s the single largest EV incentive in Australia, and the full exemption ends for new leases after 31 March 2027. Get advice before then.
• A road charge for EVs is likely someday. There’s none today (the federal one is on hold; NSW has one legislated for around 2027). At the much-discussed ~3c/km it would claw back about half an average driver’s EV saving — though petrol drivers already pay about 3.2c/km in fuel excise (the tax built into every litre — back at its full rate since August), so a fair charge levels the field rather than tilting it. Download the model and add the charge yourself to see what it does to your numbers.
• Battery life. The Dolphin’s battery is warranted for 8 years/160,000 km, and it’s the LFP type — the kind with the best record for lasting. Within ten years a replacement is unlikely. Past that, both sides carry question marks: EV batteries on one hand, out-of-warranty petrol repairs on the other. We’ve said so rather than guessed.
• What we left out, on purpose: resale differences, insurance differences (they vary widely — get quotes for both cars), and tyre wear. Any of these can nudge the answer; none plausibly closes a $680-a-year gap with a one-year payback.

The verdict

• Buying a hatchback at replacement time: EV first, hybrid second, petrol third — at every driving distance we analysed.
• Own your roof and staying put? Add solar — it roughly doubles the winnings.
• The battery is a backup purchase that’s edging towards paying its way; off-grid is for properties with no real choice.
• If energy security matters extra in your household — rural, outage-prone, or just cautious — the hybrid or a mixed two-car garage is a rational hedge that gives up surprisingly little.

Every number above comes from our published model — an Excel workbook that simulates a real household hour by hour, with every source and assumption on its README tab, and the scripts to rebuild it from raw public data. Download the model (Excel workbook, ~1 MB), change our assumptions to yours, and check us. That’s the point. (Don’t want a spreadsheet? The calculator does the car-vs-car sums in your browser.)

Next in this series: the mid-size SUV edition — where the maths takes a genuinely different turn.