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California LocalizedGenerated accuracy model review: 2026-05-06

California Gas Cost Calculator accuracy and testing

This page documents how Calwarden builds trust for this calculator: source notes, regression-style default tests, limitations, assumptions, unit handling, rounding, and visible change history.

Formula source

  • Estimated fuel cost = miles / MPG x (gas price per gallon + optional per-gallon add-on).

Test cases

Default input regression check

Generated from the checked-in default inputs and calculate function.

Inputs

  • Miles: 900 mi
  • Vehicle MPG Preset: epa_2026_honda_crv_fwd
  • Fuel Economy: 28 MPG
  • Fuel Price Preset: eia_ca_regular_gasoline_2026_05_04
  • Gas Price: 5 $/gal
  • Optional CA Fee / Tax Add-On: 0 $/gal

Expected outputs

  • Estimated Fuel Cost: $178.77

Known limitations

  • This is a planning estimate only. It is not tax, DMV, utility, or transportation advice and does not verify official fuel taxes, station prices, rebates, fuel grade differences, or local exceptions.

Assumptions

  • Miles and MPG are user-entered planning values.
  • The optional add-on is added to the entered gas price per gallon.
  • The calculator does not fetch live gas prices or tax schedules.

Unit handling

  • Miles accepts values in mi.
  • Vehicle MPG Preset accepts one of the configured options.
  • Fuel Economy accepts values in MPG.
  • Fuel Price Preset accepts one of the configured options.
  • Gas Price accepts values in $/gal.
  • Optional CA Fee / Tax Add-On accepts values in $/gal.
  • Estimated Fuel Cost is displayed as currency.

Rounding rules

  • Number displays use up to 2 decimal places in the calculator UI.
  • Currency outputs are displayed with standard US dollar formatting.
  • Input precision follows configured step values where provided.

Version history

1.0.0 - 2026-05-06

Generated accuracy and testing page from the current california-gas-cost-calculator calculator definition.

Change log

2026-05-06

Published default regression test documentation and metadata fallbacks for California Gas Cost Calculator.

Calculator transparency

Accuracy pages are generated from checked-in calculator definitions and can be upgraded with curated review metadata over time.

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