An efficiency comparison is not a price comparison
MPG measures miles per US gallon of liquid fuel. MPGe expresses electric-vehicle efficiency on an equivalent-energy basis. The electricity price is not encoded in that rating. A 120 MPGe electric car does not let you calculate its bill by dividing miles by 120 and multiplying by a gasoline price.
Use the number that matches the meter
For an electric car, use the EPA kWh per 100 miles figure and the electricity rate you actually pay. At 28 kWh/100 miles, a 1,000-mile month requires a modeled 280 kWh. At $0.17 per kWh that is $47.60; at $0.45 per kWh it is $126. The car has not changed, but the price has.
Do not count charging losses twice
EPA electricity consumption is based on energy drawn to recharge the vehicle, so a separate blanket charging-loss multiplier would double-count losses already represented in that figure. Battery capacity divided by range is a different estimate and does not automatically capture energy drawn at the wall.
Compare the whole scenario
For a gasoline car at 30 MPG, the same 1,000 miles use 33.33 gallons. At an assumed $3.50 per gallon, the cost is $116.67. Under those inputs, home electricity is cheaper but $0.45/kWh electricity is more expensive. Neither result is a universal statement about electric cars. Charging subscriptions, idle fees and other ownership costs need a separate budget.