Perhaps it's not a big surprise that some used car dealers seem to skirt consumer protection laws and sell vehicles that can't pass inspections or last 30 days on the road.

But a report released by the St. Louis Better Business Bureau on Friday suggests consumers need to bone up on their legal, consumer rights.

In eastern Missouri and Southern Illinois, the used car dealers have ranked among the top 10 industries with the most BBB complaints. There are 712 used car dealers that are rated by the St. Louis BBB, and about 14 percent of those scored grades of D or lower on the watchdog group's school-style grading system.

The study looked at area dealerships with the worst BBB track records. The BBB surveyed and interviewed more than 250 consumers who had filed complaints against the dealers.

About 42 percent chose a specific dealership because of its advertising, and most of these consumers later felt the ads were misleading.

Forty-six of the dealers with bad grades have websites. When the BBB reviewed their online claims, it found that more than a third of the sites contained misleading advertising.

Often, the misleading ads promise that credit is extended to everyone — "Guaranteed Financing," "We finance anyone!" and that sort of thing.

But, these same dealerships often require steep down payments as high as half the purchase price, and then try to hold on to that money after a return or repossession.

Buying from a questionable dealer that seems to offer cheap prices can prove expensive in the long run, or even within a month of purchase.

Fifty of the 118 consumers interviewed for the study reported losing an average of $1,044 because their cars needed expensive repairs or they lost their down payments when they took the vehicles back to the dealership. Four consumers said they were fired because they couldn't get to work after their cars broke down within 30 days of purchase.

Nineteen respondents told the BBB they took back their vehicles because they couldn't afford repairs, usually losing their down payments in the process. And 29 percent of those surveyed said their cars were repossessed, often because the owners couldn't afford both repair costs and loan payments.

Too often consumers put their faith in warranties that aren't as good as dealers make them out to be.

About half of all respondents told the BBB that a warranty was included in the purchase, but many were extremely limited — such as lasting just 30 days, requiring the dealer to pay only a percentage of the repair costs, requirements that the consumer pay for all replacement parts, etc.

Of those consumers surveyed who had a problem with a vehicle that they thought should have been covered by a warranty, more than half said the dealer refused to make the repairs.

A lot of these problem could be avoided if consumers knew their rights and learned to recognize when a dealer seems to be breaking the law.

For instance, there shouldn't be any confusion about what kind of warranty comes with the vehicle. That's because the Federal Trade Commission's Used Car Rule requires dealers to post a one-page Buyers Guides prominently in all cars for sale and to give purchasers a copy of the guide.

The guide needs to say whether a warranty is offered. If it is, the exact terms — including how long it lasts, exclusions, whether the dealer only pays a percentage of repairs, etc. — need to be spelled out. If a dealer isn't displaying buyers guides, consumers should stop shopping there and take their business elsewhere.

(In the BBB survey, 43 percent of consumers said a guide wasn't visible when they were shopping or given to them at purchase. BBB employees went undercover at six of the dealerships identified by survey respondents. At one lot, guides were visible only in two of 20 cars; at another, only half the vehicles for sale displayed guides. At the four other dealerships, only a few vehicles seemed to be missing the guides.)

Consumers also should beware if they're asked to sign a "junk" or 'salvage" affidavit.

That's a way for dealers to get around Missouri laws that require them to sell only vehicles that have passed safety inspections, which aren't required in Illinois.

A whopping 42 percent of Missourians surveyed by the BBB said their dealers failed to have the vehicles inspected before sale.