Electric cars can go 3 to 4 miles per kW-Hr. The average cost of electricity in the US is about $0.11 per kW-Hr, so if you drive 1000 miles per month, you'd be using about 350 kW-hr of power costing about $38 per month. That is about $462 per year. An electric motor is over 90% efficient.
A gasoline powered car would require 33 gallons per month at 30 miles per gallon. At today's gasoline price of $3.50, that works out to $116 per month or $1400 per year. An internal combustion engine is only 30% efficient at best.
So, just considering fuel costs, you'd save about $1000 per year with the electric car or double that amount if you drive 2000 miles per month or 24,000 miles per year. The depreciation of the electric car should be less than a complicated gasoline car since there are fewer moving parts. The battery life should be good for at least 100,000 miles, maybe 200,000 miles and it's replacement cost should come down over time. Maintenance on an electric car should be less too with few moving parts. Regenerative braking should reduce brake wear for instance. So, there could be additional savings in addition to fuel savings.
The Purchase Price is HighThe problem is that the purchase price of an electric car is high or very high. Electric cars are not selling well. Because of that, Nissan instituted a massive price cut to it's Leaf electric car. It's down to $22,000 or so for the basic model and more like $28,000 to $30,000 with desirable preferences. Toyota Prius plug-in cars run about $30,000. So, you're paying $10,000 to $12,000 more for the electric car. These are very small cars and not the luxury models. Many electric-only cars are in the $100,000 price range.
Is a 5 to 10 year payout good enough for you?
Ill-conceived Tax Subsidies For Luxury CarsThere's a $7500 government tax rebate for electric to encourage purchases, so that helps the individual (not the gov't budget deficit). This even though there are little savings in carbon dioxide emitted at the power plant that generates the power. Now, if we widely used Molten-Salt Thorium Reactors, then electricity costs and emissions would definitely come down!
Most of the electric cars are luxury models costing $100,000 for the Tesla and Fisker Karma. So why are US taxpayers subsidizing luxury car purchases---especially when there's little or no reduction of carbon dioxide gases??