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EV & CarsGenerated accuracy model review: 2026-05-06
EV vs Gas Car 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
- EV annual cost = electricity + EV maintenance + insurance difference + EV fee. Gas annual cost = fuel + gas maintenance. Payback = purchase premium / annual EV savings.
Test cases
Default input regression check
Generated from the checked-in default inputs and calculate function.
Inputs
- Annual Miles: 12,000 mi/yr
- EV Efficiency Preset: tesla_model_y_long_range
- EV Efficiency: 3.5 mi/kWh
- Electricity Rate Preset: eia_us_residential_average
- Electricity Price: 0.16 $/kWh
- Gas MPG Preset: epa_2026_honda_crv_fwd
- Gas Vehicle MPG: 28 MPG
- Fuel Price Preset: eia_us_regular_gasoline_2026_05_04
- Gas Price: 3.8 $/gal
- EV Maintenance: 450 $/yr
- Gas Maintenance: 850 $/yr
- Charging Loss: 10%
- EV Insurance Difference: 200 $/yr
- EV Registration Fee: 150 $/yr
- EV Purchase Premium: $4,000
Expected outputs
- Lower Annual Cost: EV is lower
- EV Annual Cost: $1,378.25
- Gas Annual Cost: $2,630.80
- Annual Cost Difference: $1,252.55
- Simple Payback: 3.19 years
Known limitations
- This page documents the checked-in calculator logic and does not certify results for every real-world edge case.
- Use the result as a planning estimate unless the calculator page states a stricter purpose.
Assumptions
- All prices and vehicle assumptions are user-entered.
- Charging loss is modeled as a simple percentage.
- Calculations run locally in your browser and are not stored by Calwarden.
- Results are planning estimates, not financial, tax, insurance, legal, or mechanical advice.
Unit handling
- Annual Miles accepts values in mi/yr.
- EV Efficiency Preset accepts one of the configured options.
- EV Efficiency accepts values in mi/kWh.
- Electricity Rate Preset accepts one of the configured options.
- Electricity Price accepts values in $/kWh.
- Gas MPG Preset accepts one of the configured options.
- Gas Vehicle MPG accepts values in MPG.
- Fuel Price Preset accepts one of the configured options.
- Gas Price accepts values in $/gal.
- EV Maintenance accepts values in $/yr.
- Gas Maintenance accepts values in $/yr.
- Charging Loss accepts values in %.
- EV Insurance Difference accepts values in $/yr.
- EV Registration Fee accepts values in $/yr.
- EV Purchase Premium accepts values in $.
- EV Annual Cost is displayed as currency.
- Gas Annual Cost is displayed as currency.
- Annual Cost Difference is displayed as currency.
- Simple Payback is displayed in years.
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 ev-vs-gas-car-cost-calculator calculator definition.
Change log
2026-05-06
Published default regression test documentation and metadata fallbacks for EV vs Gas Car Cost Calculator.
Calculator transparency
Accuracy pages are generated from checked-in calculator definitions and can be upgraded with curated review metadata over time.