Fuel efficiency comparison

Nine vehicle classes compared on the only basis that lets you compare them — what each one costs to move 100 kilometres, at this week’s Australian fuel prices. Consumption figures in L/100km and MPG, energy cost in dollars, and the reason a straight MPG comparison misleads you.

How does fuel efficiency compare across vehicle types?

Efficiency differences between classes are far larger than differences within them. Moving from a large SUV to a mid-size one saves more fuel than any driving technique, tyre pressure regime or fuel additive will ever recover. The table below gives indicative combined-cycle consumption for each class, converted to both scales and priced at current Australian averages.

Why does comparing MPG mislead you?

Because the MPG scale is not linear in fuel used. Going from 20 to 25 MPG saves 2.4 litres per 100 km. Going from 40 to 45 MPG — the same five-mile-per-gallon step — saves only 0.8. Ranking two vehicles by MPG tells you which is more efficient, but the size of the gap between them is systematically distorted, and always in the direction of making improvements at the efficient end look bigger than they are.

L/100km does not have this problem: it is linear in fuel, so a difference of 2 L/100km means the same amount of fuel wherever it sits on the scale. This is why Australia, and most of the world outside the US and UK, uses it. If you have MPG figures, convert with L/100km = 235.215 ÷ MPG before comparing, or use the fuel economy calculator.

MPG to L/100km conversion table

Divide 235.215 by the MPG figure to get L/100km, and divide 235.215 by L/100km to go the other way. The same constant works in both directions because the two scales are reciprocals. Common values:

For a value not in the table, the fuel economy calculator converts either way and prices the result at current Australian fuel prices.

Is a hybrid, an EV or a petrol car cheapest to run?

On energy cost alone, an EV charged at home off-peak wins comfortably, a hybrid comes second, and a petrol or gas car of the same size comes last. At 16 kWh/100 km and a 28 c/kWh off-peak tariff an EV costs about $4.48 per 100 km, against roughly $8.43 for an efficient hybrid and $17.06 for a mid-size petrol SUV.

That ranking flips on two conditions. Charge mostly on public DC at 65 c/kWh and the EV lands near $10.40 per 100 km — worse than the hybrid. And energy cost is not purchase price: a premium of $12,000 takes years of savings to recover, and how many years depends almost entirely on your annual distance. The EV vs petrol calculator and the hybrid vs petrol calculator work the break-even out at your own numbers.

How much of the published figure will you actually get?

Expect 10–20% worse than the manufacturer’s combined WLTP rating, and worse again in specific conditions. The rating is measured on a standardised cycle; your commute is not that cycle. Four things move real consumption furthest from the brochure:

• Short trips from cold. An engine below operating temperature can use 30–50% more fuel for the first few kilometres. A 5 km commute may never leave that band.
• Speed. Aerodynamic drag rises with the square of speed and the power to overcome it with the cube. Highway consumption at 110 km/h is materially worse than at 90.
• Load and shape. A roof box or a towed trailer changes frontal area, which matters far more at highway speed than the weight does.
• Tyre pressure. Under-inflation raises rolling resistance on every kilometre you drive, and it is the only item on this list that costs nothing to fix.

What is a good fuel efficiency figure in Australia?

For a small car, under 6.5 L/100km is competitive and under 5 is very good. For a mid-size SUV, under 8 is competitive and under 6 usually means a hybrid. For a dual-cab ute, under 8.5 is good and anything under 8 is exceptional. Heavy 4WDs rarely beat 12 in real use regardless of the rating.

The more useful test is not the number but the cost: work out what your current vehicle costs per 100 km from the table above, multiply by your annual distance, and compare that against the vehicle you are considering. A 2 L/100km improvement at 15,000 km a year is worth about $602a year at today’s petrol price — useful, but rarely enough on its own to justify changing cars.

People usually arrive at this question holding one number — the figure their own car returns — and wanting to know where it sits. This table answers that directly.

Two caveats before you judge your own figure. Read it against your vehicle’s class, not against the table’s midpoint — 9 L/100km is unremarkable in a large SUV and poor in a hatchback. And read it against how you drive: a short urban commute will sit two or three litres above the same car’s highway figure, and that is normal rather than a fault.

If your figure is more than about 20% above the manufacturer’s combined rating and your driving has not changed, that is worth investigating — tyre pressure first, then air filter, then a service. A sudden jump usually has a mechanical cause; a gradual drift usually does not.

Where these figures come from

Consumption figures are indicative class midpoints drawn from manufacturer combined-cycle ratings for common Australian models, rounded to one decimal. They are a starting point for comparison between classes, not a specification for any individual vehicle — for that, measure your own litres per 100 km across a few full-tank fills.

Fuel prices are transcribed from a single named ACCC weekly report and republished in full, with the retrieval date, on our Australian fuel price data page. Because fuel excise moved twice in 2026, any comparison built on prices from earlier this year understates running costs by a wide margin.