Sales were strong, but could clunkers program end with a thud?

The government says the Cash for Clunkers program spurred nearly 700,000 sales of new cars this summer. That would seem like a boon for ailing automakers. But is it really?

The answer will hinge on what happens to auto sales in the coming months. And an analysis by car information site Edmunds.com suggests that it's going to be a lean fall for the likes of Toyota (TM), Ford (F), Honda (HMC) and Nissan (NSANY), makers of the most popular car models among consumers trading in old vehicles under the clunkers program.