General Motors ran out of cash and crashed into bankruptcy court in early 2009, and the point of the "fortress balance sheet" approach was to institutionalize the lessons learned from that experience so that it never happened again. Obviously, $25 billion is a better nest egg than $20 billion. But $20 billion is still enough to fund GM's level of investment for a little over two years at current rates. As long as GM maintains access to credit at investment-grade rates, that should be sufficient -- but we'll see.