Calculator assumptions

The full assumption set behind the save-on-fuel calculators and the EV comparison: inputs, rates, sources, and the caveats that bound each estimate.

Calculator assumptions

The full assumption set behind the save-on-fuel calculators and the EV comparison

Editorial assessment

The full assumption set behind each calculator. Open a row for the inputs and caveats.

Fuel cost calculator

Annual litres equals (km divided by 100) times L/100km; annual cost equals annual litres times price per litre.
ULP 91 and diesel use the live national retail median. Premium 95, Premium 98 and LPG use the live national median where enough states report it, otherwise an estimate from typical price spreads over ULP; E10 is always estimated at ULP minus about 4 c/L. Estimated figures are labelled in place of the "Live" marker.
The pre-crisis baseline uses the most recent value recorded before the wholesale step-up, per the fuel-prices feed.
Where a figure is quoted per fill rather than per year, the tank is 65 L. That is the standard household example used across the site, taken from the Prime Minister's 20 June 2026 framing of the excise saving; your own tank may be larger or smaller.
The calculator uses a conservative real-world average of about 6 c/km (roughly 18 kWh/100km on a blended home tariff near 33 c/kWh, allowing for some peak and occasional public charging). The model-specific EV comparison below uses each car's WLTP efficiency at 30 c/kWh off-peak grid charging, so those figures sit a little lower, about 4 to 5 c/km. No per-kilometre road-user charge currently applies to electric vehicles: the High Court struck down Victoria's distance-based charge in Vanderstock v Victoria [2023] HCA 30, and no Commonwealth scheme has replaced it.
Inputs are capped at 26,000 km/year and 15 L/100km to keep savings figures within realistic bounds.

EV comparison

Fuel-cost saving assumes 15,000 km/yr, petrol at 8.5 L/100km, EV efficiency per model (WLTP combined), and grid charging at 30 c/kWh, priced against the current national-average petrol price (the /save-on-fuel table updates as pump prices move). Home solar charging improves the EV figure.
The FBT-exempt novated lease benefit is indicative at $85,000 gross salary and 34.5% marginal rate. It exists only if your employer offers salary packaging; actual benefit depends on salary, residual value, lease term, and employer policy. The Electric Car Discount FBT exemption is being wound back (announced in the May 2026 Budget; not yet legislated): the full exemption runs to 31 March 2027, then from 1 April 2027 it is kept only for EVs priced $75,000 or less (a 25 per cent FBT discount applies above that, up to the luxury car tax threshold), and from 1 April 2029 the 25 per cent discount replaces the exemption for all eligible EVs. Existing leases are grandfathered for their term.
Maintenance saving reflects fewer mechanical components; source RACV cost-of-ownership comparison, April 2026.
Grid-mix caveat: most NEM electricity is still fossil-generated (AEMO), so the well-to-wheel emissions saving is smaller than the cost saving implies. Depreciation caveat: EVs currently depreciate faster than petrol equivalents in the Australian used market; factor resale into total cost of ownership.
When an EV may not save money: long regional commutes without charging access, apartments without allocated charging, towing needs above current EV ratings, or low annual kilometres.

Novated lease calculator

Marginal tax rate uses ATO 2025-26 resident brackets plus the 2% Medicare levy.
Annual running cost is an indicative RACQ 2025 figure covering tyres, insurance, servicing, and rego.
GST saving is estimated at 9.09% of the drive-away price, spread over the lease term.
The FBT exemption applies to eligible vehicles under the luxury car tax threshold. The Electric Car Discount FBT exemption is being wound back (announced in the May 2026 Budget; not yet legislated): the full exemption runs to 31 March 2027, then from 1 April 2027 it is kept only for EVs priced $75,000 or less (a 25 per cent FBT discount applies above that, up to the luxury car tax threshold), and from 1 April 2029 the 25 per cent discount replaces the exemption for all eligible EVs. Existing leases are grandfathered for their term.
For home-charging substantiation, the ATO PCG 2024/2 indicative rate is 5.47 c/km (effective 1 April 2026); most novated-lease providers reimburse home electricity at this rate.
Inputs are clamped to sensible ranges so an accidental extra zero cannot blow out the savings maths.

All calculator outputs are illustrative guides, not financial advice. Individual savings vary with driving pattern, tariff, employer arrangements, and vehicle efficiency.

Editorial assessment

Last updated: Reviewed 9 July 2026 Source: ATO, RACV, RACQ, AEMO; model data verified April 2026

Questions about our methodology?

Stay updated on how we build this

We will notify you when we add new government data sources, refine our calculations, or issue corrections. Full transparency, no surprises. For specific verification requests, email info@fuelcrisis.com.au.

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For developers: the internal codebase identifiers behind each formula and data source are documented in docs/ABOUT-DATA.md on GitHub.