Quick Answer — How Much Cheaper Is an E-Bike Than a Car, Per Mile?
An e-bike typically costs 20-30 watt-hours per mile to run. At a residential electricity rate of $0.1883/kWh, that's about $0.0047 per mile — well under half a cent. A car, by comparison, costs its fuel price divided by MPG just for gas, plus a realistic per-mile allowance for maintenance, tires, and insurance wear — commonly $0.15-$0.30+ per mile all-in, depending on the vehicle and how it's driven.
Quick reference (50 miles/week, 30 mpg car, $3.50/gallon gas): Switching those miles to an e-bike saves about $551/year including a modest $0.10/mile car-maintenance allowance, and avoids about 0.77 metric tons of CO2 per year. Double the weekly mileage to 100 and the savings scale up proportionally to over $1,200/year.
The gap is this large because gasoline and e-bike batteries are wildly different in energy density and use case — a car engine converts gasoline to motion at roughly 20-30% thermal efficiency and moves 3,000+ lbs of vehicle, while an e-bike motor assists a rider who is already providing most of the propulsion themselves.