Fuel efficiency for Tesla: 3 miles/kilowatthour. And here are the results: Cost of electricity to drive the Tesla 23,000 miles: $1,226. Cost of premium gas to drive BMW 7 Series 23,000 miles: $4,951. Money saved on fuel by driving Tesla: $3,724.Obviously, there are many factors that could change the result of these calculations.uel efficiency for Tesla: 3 miles/kilowatthour. And here are the results: Cost of electricity to drive the Tesla 23,000 miles: $1,226. Cost of premium gas to drive BMW 7 Series 23,000 miles: $4,951. Money saved on fuel by driving Tesla: $3,724.