Tesla used some very shaky math last month to come up with what it called a $500-per-month sales plan for the new Model S sedan — even though customers would be paying over $1000 per month. Tesla cofounder and CEO Elon Musk has now admitted that the pricing plan wasn't completely up-front with customers. Musk said on a call to press today that "when we did our first financing announcement, we didn’t get it quite right. And we're looking to a lot of valid criticism from journalists and customers, and so we've tried to take corrective action and make it a lot better." To address the problem, the company has updated its payment calculator tool to no longer count some outlandish deductions — like $100 per month in "time savings" from skipping gas stations.

Alongside the update to its online calculator, Tesla is introducing a new 72-month financing plan (that's nine months longer than was previously offered). By stretching out payments over some more time Tesla says that customers could possibly be paying as little as $580 per month, when taking into account gasoline savings and tax credits — a number that is still significantly higher than what you'll be actually be paying out of pocket every month ($916 for the 60kWh model). The company is also making "a guarantee that the resale value will be higher than that of BMW, Audi, Mercedes, Lexus or Jaguar" — and its "estimated monthly cost" spreads out that resale value over the length of the financing plan.