SKILL.md
EV vs Gas Skill
The EV question is a crossover question: a higher price tag melting under lower running costs, with the answer living in your numbers — miles driven, electricity price (home vs. public charging are different products), and how long you keep cars. This skill runs the cumulative math year by year and reports where the lines cross, then is honest about what the model can't see: battery risk, a resale market still finding its feet, and the charger install that belongs in the purchase price.
What This Skill Produces
- The cumulative table — EV vs gas total cost per year over the horizon, from the script
- The crossover year — where the EV pulls ahead, or the finding that it doesn't within the horizon
- The per-year energy math — miles ÷ efficiency × price, both sides, shown not asserted
- The not-modeled list — battery, resale, charger install, price drift — stated up front
Required Inputs
Ask for these if not provided:
- The two candidates' prices — the actual EV and the comparable gas car (same class — comparing a luxury EV to an economy gas car answers a different question); applicable incentives, flagged as verify-eligibility
- Annual miles — the single biggest lever; low-mileage drivers should see how far the crossover moves
- Electricity reality — home charging rate if they have it, or an honest blended rate if they'd rely on public charging (often 2–3× home rates — it can erase the fuel advantage; say so)
- Ownership horizon — a crossover at year 6 means opposite things to a 3-year and a 10-year keeper
Programmatic Helper
python3 scripts/ev_vs_gas.py --ev-price 42000 --gas-price 33000 --incentive 7500
python3 scripts/ev_vs_gas.py --ev-price 42000 --gas-price 33000 --miles 15000 --kwh-price 0.16 --gas-price-gal 3.60 --json
Deterministic. Defaults are labeled and overridable: 3.3 mi/kWh, 32 mpg, $0.15/kWh, $3.50/gal, maintenance $500 vs $900, +$150/yr EV insurance. Home-charger install cost belongs added to --ev-price.