I think they've just announced that they will be the first EV company to start paying their debt to the Government by the end of the year or something. If there's a good side to Government funding at all, it's this - investing in future technology that starts being useful right away, and can become mainstream within 10 years, which is a much better investment than subsidizing something like the oil industry for many decades, even though they keep scoring record profits.
If it can become useful and mainstream right away, why do they need government funding?
And to point out the obvious, the Federal government extracts far more money from the oil companies (and hence oil consumers) by way of gas taxes than it pays out in subsidies.
As I see it, the government's real pay-off isn't Tesla paying back it's loans, but rather is the increase in energy policy flexibility that is gained if EVs become popular. If it's easier to provide energy security, that reduces military burden and also reduces our need to be involved in some unfriendly parts of the world.
This payoff can't be captured by a private investor, so the government has incentive to invest earlier (and at higher risk levels) than private investors.
I can't find the half billion figure for Tesla in that article (only for Fisker).
Also, Tesla is a public company and therefore discloses their finantials. Their total debt is 270M, and they have 280M in cash (therefore, negative net debt).
http://techcrunch.com/2009/06/23/the-government-comes-throug...
Coal is majority of the U.S. power grid: http://www.ucsusa.org/clean_energy/coalvswind/c01.html
Tesla batteries are cleaner than older versions, but they contain some Cobalt, and Lithium has many impacts and risks for humans.