I'm not an American, but I am on some car related forums that are primarily US based, so I did see some of the things that were said on this. All in all, I think the program's 'success' is relative. If you say success based on the fact the funds were expended so fast, then yes. If you say success because you could possibly buy a car cheap with the process, then maybe, but if you say success because it's a massive benefit for the US economy, then no.
The government gives you money if you trade in a car for a car that runs atleast 2 MPG's more efficient. This car has to be one from an approved list of vehicles. This list only contains more environmentally friendly vehicles, since the government is so hung up on getting the US population to drive more environmentally friendly.
So if we look at the list... How much is actually going toward the industry that is the 'face' of the problems in the car manufacturing? The so called 'Big Three', or by now 'Big Two'? Well, the list contains a heap of cars, but some 15 to 20% is Ford and General Motors. The majority of the list goes to non US brands like Toyota for instance. So most money spent might very well not contribute the US economy at all. While partly there might be manufacturing plants in the US for those brands that benefit, part of the money is still going to go abroad. Not by fault of the government tho. They're supposed to provide a level playing field for everyone on the market.
What the government of the USA however is forgetting is the fact that GM and Ford never really needed or cared to make a lot of environmentally friendly cars. Driving a car in the US is cheap, and as such the weight of public demand was on the bigger and more environmentally unfriendly cars. The governement stepped in there with the CAFE standards, demanding that for every 'gas guzzler' and equal amount of smaller more economical cars would be made, so the average MPG of the entire fleet of that manufacturer would rise to a certain value. So the government demanded the Ford and GM produced more smaller and environmentally friendly vehicles, while the public didn't want those. The result, a lot of spent money on the manufacturers side, loads of smaller cars on the lot with no people to buy them, which is what partially caused the whole issue with the auto industry.
In Europe we don't press the manufacturers to make more small cars. We raise taxes and gas prices and end up with the public demanding it. The manufacturer will tend to the requirements of the public and the same result is reached. America tries to do it the other way around: provide for something, and the public will switch on it's own, seeing there isn't an option to take something else available anymore.
Now as to the program, personally I see the destruction of a 'clunker' as a destruction of resources and money. It's foreseeable that anyone buying a car would be trading up. So why destroy a 'clunker'? If someone else comes along that can adhere to the trade-up by the 2 MPG, and buy said 'clunker', you'll be providing more revenue for the auto industry and let someone else that could possibly not afford a new vehicle trade up thus going more environmentally friendly on the second stage as well.
I've seen the destruction of the vehicles on Youtube (
http://www.youtube.com/watch?v=JlVljhcnul0 ), and it honestly hurts me to see a car that looks good, isn't that old, and runs fine (and could provide a good deal of miles more) being destroyed by the process.
All in all, the program isn't yielding the benefits to the economy it could have based on the fact that part of the money might never see a return into the US economy, and the fact that there are a lot of 2nd hand cars that are still very good are being taken off the market completely (that's gonna leave a gap in the oldtimer fleet in about 20 to 30 years), instead of being marketed yielding more economic transactions/benefits.