Buy a Model S and Tesla promises that in six months you'll be able to drive from Los Angeles to New York without paying a dime to top up your batteries.

That's just one part of an ambitious plan to expand Tesla's Supercharger network, a series of solar-powered charging stations that will stretch from coast to coast by next year and allow Model S owners to recharge their rides in 20 to 30 minutes. For free. Forever.

Tesla's announcement, which Elon Musk hinted at during his talk at AllThingsD 11, is a dramatic acceleration of its initial Supercharger roll-out plan. When Tesla originally introduced the network last October, the automaker intended to line the major highways across the country with Superchargers over the course of a few years. But this new initiative ramps up that expansion considerably.

Currently, Superchargers serving the west coast are installed in parts of California and Nevada, with the east coast covered from Washington, DC to Boston. But by the end of next month, Tesla claims it will triple the number of Supercharger stations in the Golden State, along with adding new stations along the major corridors serving the northwest, connecting Vancouver, Seattle and Portland. Austin and Dallas, in Texas, and Illinois and Colorado are also on the near-term road map, including the addition of four new stations on the eastern seaboard to "provide for more convenient stopping points."

In six months' time, Tesla says Superchargers will "connected most of the major metro areas in the U.S. and Canada," with expansions from Arizona to Florida, Ottawa to Montreal and throughout parts of the south, including Georgia and North and South Carolina. And within the next year, Tesla says Superchargers will cover "almost the entire population of the U.S. and Canada", so "Model S drivers can take the ultimate road trip – whether that’s LA to New York, Vancouver to San Diego, or Montreal to Miami."

Tesla estimates that Superchargers have helped Model S owners cover over one million miles since its introduction late last year, but insists that improvements can still be made to the charging technology.

"In addition to the expansion of the Tesla Supercharger network itself," the automaker said in a statement, "Tesla is improving the technology behind the Tesla Supercharger to dramatically decrease the amount of time it takes to charge Model S, cutting charging time in half relative to early trials of the system."

This new charging tech, which is currently in beta testing, claims to allow owners to add an additional three hours of drive time through a 120 kW line in "just over 20 minutes." And in true Silicon Valley fashion, Model S owners will receive an update to their vehicle's software this summer to implement the new fast-charging protocol.