New Tesla vehicles purchased before January 15th will be able to top-off for free at any Supercharger station, same as always -- but cars purchased after the date will be limited to just 400 kWh of free energy per year. Tesla says that's enough to drive about 1000 miles. Charging beyond that will cost an unannounced additional fee, but the company says it won't be too expensive, claiming it will cost drivers "less than the price of filling up a comparable gas car." That doesn't sound too bad, but if you were saving up to buy a Model S anyway, maybe buy it sooner rather than later.