Cash for Clunkers is over. Whether it was a success or whether it was another government boondoggle depends upon one's point of view.

Car dealers are telling the media that they have a backlog of cash for clunkers cars which they have accepted but the government hasn't paid them as yet.

Worse, about 80 per cent of the requests for payment are being rejected according to an Automotive News survey.

Rick Newman of U.S. News and World Report reported last week that it turns out that delivering a couple of billion dollars' worth of rebates for hundreds of thousands of car purchases can generate a few flat tires.

The Department of Transportation's latest update on the Car Allowance Rebate System (CARS) shows that the government has received applications for about 412,000 rebates totaling $1.7 billion. But so far, the feds have approved only a fraction of those, leaving dealers furious and holding the bag.

The Transportation Department won't say exactly what the rejection rate is but in an Automotive News survey, some dealers said up to 80 per cent of their rebate applications had been rejected.

The survey found that some dealers say that they are waiting for payments totaling as much as $200,000.

A large number of dealers, particularly in New York abandoned the program before it concluded last Monday.

The reason given was too much red tape and concern about getting paid by the government.

The dealer must stamp the title "Junk Automobile, Cars.gov" before submitting a voucher for reimbursement. And the dealer must have clear title before doing so.

This has caused a lot of dealers severe cash flow problems according to Fox News.

"I know dealers are frustrated," Secretary Ray LaHood told the New York Times last Wednesday.

Many dealers are worried that they will never be reimbursed for credits they have given customers.

The backlog of cars has already pushed many dealers, to refuse more trade-ins under the program before it ended.

"I'm a small store," said Ron Morehead Jr., general manager of a Honda dealership in Kingston, N.Y. told Jack Healy of the New York Times. "The well runs dry."

Mr. Morehead said he had paid out $225,000 in rebates since the program began last month but had been reimbursed for only one deal, which he filed with the government on July 28.

Meanwhile, he said, he still had to pay his 30 employees, pay his bills and repay the bank when he sold a car.

A week before the program ended Mr. Morehead quit according to the Times.

"I've lost 15 to 20 deals because of it," Mr. Morehead said. "But you know what? We're still doing business. I can't afford to keep sending money out. It's time to get paid."

In some cases, buyers are being asked to pay the dealer $4,500 if the government turns down the dealer's claim. That means that people who think they have paid for their new car completely may find later down stream that they have not and that the dealer is after them for more money.

It's obvious that the National Highway Traffic Safety Administration [NHTSA], the agency administering CARS, has been overwhelmed by the popularity of a program that has surprised just about everybody, including the masterminds in Congress who had to triple the funding a week after clunkers kicked in.

The NHTSA initially detailed 225 people to process those 400,000 claims. Then, it had to assign 1,000 more workers just to go over the paperwork.

To put this in context, there are only about 635 full-time workers at the entire agency and their principal job is to set safety standards, perform crash tests, conduct research and regulate the automakers. So the NHTSA swelled temporarily to twice its regular size by borrowing workers from other agencies to manage a program that came to an end prematurely.

But the buying spree, fueled by government rebates of up to $4,500, may not be quite the economic boost it appeared to be on the surface.

Having to end it before it was supposed to end makes it look like there were some of those pesky unintended consequences.

Here are a few reasons that cash for clunkers is likely to look a lot less successful when seen in the rearview mirror:

Some of those car purchases would have happened anyway.

Analysis from carresearch site Edmunds.com found that at least 100,000 car buyers put off a purchase earlier this year to take advantage of cash for clunkers once they learned about it.

More than likely, those sales would have happened even without the government giveaway.

Analysis of the steep discounts offered in 2001, after the 9/11 attacks, has shown that most buyers who took advantage of the sales simply moved up their planned purchase by a few months, creating a "payback" effect when sales dipped several months later.

"We have crammed three to four months of normal activity into just a few days," wrote Edmunds CEO Jeremy Anwyl in an Oped to the Wall Street Journal.

This could cause car sales to dip again this fall, slowing any momentum gained over the summer Mr. Anwyl believes.

The used-car market might go haywire.

Since clunkers that get traded in have to be destroyed, the program could take 750,000 vehicles out of the used-car market.

That is about 5 percent of the market, according to kbb.com. That is enough of a contraction to cause significant price hikes for used vehicles.

Kbb.com predicts there will even be a used-car bubble with a shortage leading used-car dealers to stock up on inventory.

When the clunker rebates end, dealers could end up with too many cars, causing prices to seesaw the other way.

A serpentine sales curve makes it much harder to manage a business and earn profits than a nice steady one.

Drivers could end up burning more gas.

Drivers may have traded in their old car for one that gets significantly better mileage to qualify for the rebate.

With a fresh ride in the driveway, buyers are likely to change their driving habits.

Surveys by research firm CNW Marketing Research have found that clunker up-graders drove their old vehicle about 6,200 miles in 2008, barely half the typical annual mileage of 12,000.

Most of those same drivers said they'd drive their new car more and take longer trips. CNW's math shows that if clunker up-graders drive just 90 percent of the annual average mileage in the first year of ownership, they'll end up burning an extra 61 gallons of gas, even though they get better mileage.

Multiply that by 750,000 vehicles, and cash for clunkers would result in an additional 46 million gallons of gas being burned.

As a consolation, the program will unambiguously cut down on greenhouse gas emissions, since today's cleaner engines more than make up for extra miles driven. CNW pegs the greenhouse gas reduction due to clunker retirement at 92 percent or more.

Sticker prices could rise.

For the past 18 months, there's been an oversupply of cars, since virtually all automakers failed to anticipate the sharp plunge in sales.

The excess inventory has made it a buyer's market, with historic deals available on many models.

Automakers have curtailed production and whittled down their inventory, gradually bringing it in line with demand.

Now, the sudden spike in demand generated by the clunker program created unexpected shortages of some models.

That's the kind of problem the automakers don't mind, because it allows them to raise prices.

Buyers who don't qualify for a clunker rebate will be more inclined to notice that prices are up and choice cars are harder to find.

So did it spur business? I think that it certainly did.

Was it worth it? Probably.