PHEV & EREV Savings Calculator
Plug-in hybrids only pay off if you actually plug them in. Pick a vehicle, tell us how far you drive on weekdays and weekends, and we'll show how many miles run on battery vs gas — plus what you save vs. an equivalent gas car, vs. a full EV, and vs. just running it on gas.
Electricity rate in use
16.5¢/kWh · US average — EIA API key not configured
Set EIA_API_KEY in your environment (free key from eia.gov/opendata/register.php) to enable state-specific rates.
Cost assumptions
Your driving split
On battery
100%
200 mi/week
On gas
0%
0 mi/week
Total weekly miles
200
10,400 mi/year
Annual fuel cost
PHEV — plugged in
$498
$498 elec + $0 gas
Same PHEV, unplugged
$1,040
gas only @ 35 mpg
Gas car (28 mpg)
$1,300
equivalent ICE
Full BEV
$460
2017 Tesla Model 3 Long Range
Annual savings
vs. not plugging in
+$542/yr
cheaper than running this PHEV on gas
vs. gas car (28 mpg)
+$802/yr
cheaper than an equivalent gasoline car
vs. 2017 Tesla Model 3 Long Range
−$38/yr
more than a 2017 Tesla Model 3 Long Range — gas miles are the gap
- Annualized as 5 weekdays + 2 weekend days × 52 weeks. Assumes you can plug in every night.
Heads up: Electricity costs use your state's residential rate, assuming you charge at home overnight. Public DC fast charging (rare for PHEVs) and workplace charging will swing the math differently. PHEV gas-mode MPG and the comparison ICE MPG are adjustable below — defaults are sensible midpoints, not your specific car.
Data sources
- AFDC — battery kWh, electric range, PHEV / EREV architecture for current-MY vehicles. (afdc.energy.gov)
- EPA fueleconomy.gov — battery, range and efficiency for historical PHEVs (battery kWh derived from combined efficiency × range).
- US EIA — state-level residential electricity rates. (eia.gov/electricity)
- Savings math:
lib/utils/phevSavingsEstimate.ts.