Unless you're a Tesla owner with access to free Supercharger fast charging stations, there's no better place to charge your electric car than at home.

Pick the right electricity tariff, and charging can cost pennies on the dollar next to even the most efficient combustion-engined vehicle.

BMW hopes to make it even cheaper for BMW i3 and i8 drivers, with a new Smart Charging App (via Autoblog Green).

The app, initially available to BMW's 'Electronaut' early adopters but launched for all customers in 2015, could save BMW customers up to $400 a year on their electricity bills.

MORE: BMW i3 Electric Car Buyers: Mostly New To BMW (But Not i8 Owners)

Developed with software company Genability, the Smart Charging App gives customers a direct connection to a national energy rate database.

With this information, i3 owners can determine the best time for charging, when rates are lowest. It provides complete transparency over charging costs, and owners can also use it to plan and automate charging in advance.

"We are offering BMW i customers greater convenience and helping them conserve energy while maximizing their cost savings," says U.S. BMW i project manager Jose Guerrero.

MORE: Watch The BMW i3 Electric Car Park Itself, As Owner Reacts (Video)

Julian Lienich, project lead at BMW, adds "The BMW Smart Charging App provides BMW i3 drivers with an easy-to-use app that is integrated with the vehicle."

Working through BMW's i Remote App, the new system adds charging cost and time information to more familiar remote EV functions--such as preconditioning the car's climate control system or viewing the vehicle's charging status.

Electric car owners already enjoy the ease of charging their cars at home, starting up every morning with a full battery. Now, BMW i3 owners have an even more efficient way of saving money as they do so.


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