2019 vehicles average 27 MPG. They will travel an average 13,500 miles a year for an average of almost 7 years. The average price for gas over the last 7 years was $2.88 a gallon. The average price for electricity is 13.3¢ a kWh.

Chevrolet Volt - 310 watts per electric-only mile
雪佛兰博尔特--280瓦/英里
远程特斯拉Model 3-260瓦/英里
Toyota Prius Prime - 250 watts per electric-only mile

This graph doesn't factor in the savings from maintenance. Purely electric vehicles have 1/10 the moving parts which means less wear and tear. There are no oil changes, very little brake wear because of regenerative braking and in some cases no service schedule. Modern electric vehicles have batteries that can last 15-20 years.