width=598Say what you like about the $3 billion Cash-for-Clunkers program, it has been a major success at getting people into dealerships and replacing older, lower-gas mileage vehicles with newer, higher-mileage ones.

But now, it's apparently out of cash. Again. As our sister site GreenCarReports says, the National Association of Auto Dealers (NADA) warned dealers yesterday they are at risk of not getting reimbursed if they make new clunker deals.

It also asked the US government to suspend the program as of midnight last night. Problems with reimbursement led General Motors to announce this morning it would offer dealers interest-free 30-day loans for up to their total amount of outstanding clunker rebates.

But here's the big question: Will Congress take up the issue of allocating a final $1 billion to the Car Allowance Rebate Systems (CARS) program after returning from its summer recess? The program was originally conceived for $4 billion of funding, so it may be possible.

That wouldn't happen until well after Labor Day, which is how long the latest funding was supposed to last for. Until then, it appears that all the clunker cash is largely spoken for.

The total of $3 billion in funding came in two stages: an initial $1 billion that lasted barely one week, and then a second allocation of $2 billion . It's that second amount that now appears to be exhausted, based on NADA's projections from a sample of its dealers.

If you are interested in trading in your clunker but haven't done so, watch the news carefully and keep in touch with your dealer. If or when further funds become available, that will likely to be your very last chance. That's the time to go for it.