1. Ford Expedition
2. Ford F-150
3. Auto-trans BMW
4. Toyota Prius
5. Ford Focus
6. Dodge Durango
7. Ford Taurus
8. Mercury Sable
9. Older Toyotas
10. GM Dex-Cool

Most of us don't like to shell out $20,000 or more for a new car or truck, and it's tempting to believe that we can buy a model that's a few years old and get something that's almost as good as new, for a lot less money.

There's no doubt this can happen, but it's by no means a sure thing. A crafy consumer who sets out to buy a used vehicle knows that the first thing to do is to check out the best-known foibles of the models he's likely to come across in his search.

You won't find this information in the reviews that were published when the car or truck was introduced, and it's not likely you'll find it in auto magazines. You most certainly won't find it out from the dealer. So, where can you find it? On the Internet, of course, where consumers go to vent, probe and share information.

We combed through ConsumerAffairs.com's database of more than 215,000 complaints to find the ten recent-vintage models that consistently bedevil their owners with one or more serious shortcomings. Admittedly, this isn't a scientific sample but behind every complaint we receive is a consumer who would have been a lot happier -- and a lot richer -- if he or she had picked a different model when out shopping around.

Caveat: We hear more about the most popular models, the ones that sell hundreds of thousands of units. Thus, while a Ford Expedition may be more reliable than a Maserati, there just aren't enough Maseratis out there to generate a large number of complaints, no matter how infernally frustrating they may be.

1. Ford Expedition,
2. Ford F-150 and Super-Duty Trucks

Ford truck owners are usually fiercely loyal to their Blue Oval powerhouses -- until one of them spits a spark plug.

The Ford Motor Co. has turned an automotive backside to almost every customer complaining of a spit spark plug, leaving them the option or repairing the truck and keeping it or dumping the vehicle on the used-truck market.

ConsumerAffairs.com recommends that you avoid the 1998 through 2003 Ford Expedition no matter the guarantee or promise that accompanies the truck. Thousands of first and second Expedition owners have suffered a spit spark plug and paid Ford thousands of dollars to repair the defect.

Fixing the damage does not guarantee it won't happen again. Many consumers have told us they have fixed a blown plug only to have the engine spit a second or third plug.

More and more Ford mechanics and technicians are siding with consumers, charging that the troubled automaker is fully aware of a major flaw in Ford engines that causes the power plant to spit out spark plugs at random and without warning.

The mechanics complain that Ford is covering up the defect while squeezing and short-changing technicians and mechanics tasked with repairing the problem for Ford consumers.

The trouble is, no one is listening to the warning and Ford continues to stonewall and cover up the spit spark plug hazard, according to one Ford technician.

A Master Ford Technician told ConsumerAffairs.com that the situation regarding these engines and the spark plugs blowing out is not unknown to Ford.

Quite the contrary, they are well aware of it and have been since the 5.4 liter Triton engine was released, this Ford mechanic said. This same concern also affects other engines in Ford's modular engine family, such as the 4.6 liter single overhead cam V-8s and the 6.8 liter single overhead cam V-10, he warned.

Ford dealerships routinely insist to consumers complaining about a spit spark plug that they have never heard of such a thing happening.

Many Ford models are also prone to catch fire while parked, so if you buy one, park it outside. And never leave children, pets or disabled people alone inside -- even for a minute.

3. BMWs with Automatic Transmissions

The popular German car is easily found around prestige used-car lots because so many people lease the luxury cars, turning them back to BMW when the lease is over. The automaker then sells the used vehicle -- often as a "certified" cream puff -- adding to an already profitable transaction.

The people who lease the car new are the ones who got a good deal: they drove the car of their dreams for a few trouble-free years at a relatively inexpensive price.

But second and third owners are finding the automatic transmission in the German car to be unreliable and expensive to repair. Our readers report that the automatic gear box is causing no end of trouble and BMW has left them high and dry with several thousands of dollars in repair bills.

To date, the highly profitable automaker has refused to accept any responsibility for the mounting number of failures, even telling some consumers the company has never been seen the failure.

"We are unaware of any widespread concern regarding the transmission. However, the actual length of life of any given vehicle part is dependent on a number of factors including care, maintenance, use, and climate," BMW AG wrote to the owner of a 2002 3-series sedan.

The complaints being filed with ConsumerAffairs.com are similar and describe a transmission that hesitates or refuses to be shifted into reverse.

"Lost reverse gear on my 2001 330Ci convertible at about 53,000 miles," wrote Don from Dayton, Ohio. "The car has an automatic transmission and repair costs at a local dealership was $4,048," he told ConsumerAffairs.com.

Don wrote to BMW "several times but got no resolution to the problem," he said. "Numerous other people have complained of this problem with BMW automatic transmissions but BMW refuses to correct the problem," he told us.

BMW owners report that the expensive transmission failures show up most often in 3 series cars as well as the X3 and X5 BMW SUVs.

Buy a second-hand BMW with automatic transmission at your own risk. Despite the hundreds of reports citing similar problems, BMW stands by its denial.

"During the life of a vehicle, it is natural to expect that some parts may have to be replaced due to mechanical failures, or normal wear and tear. For this reason, we do not have an estimated life expectancy for components or parts of a vehicle," the company said.

That includes the transmission, according to the official BMW company line.

4. Toyota Prius

The Toyota Prius is proving to be a good, solid car but as the hybrid approaches 100,000 miles a number of odd problems are popping up that ought to be cause for concern among consumers shopping for a secondhand hybrid.

The Japanese automaker began selling gas-and-electric cars ten years ago and is now the acknowledged hybrid leader in the automotive industry.

But a growing number of ConsumerAffairs.com readers are reporting that the Prius hybrid technology is not aging well. With some Prius models in the U.S. on the road now for eight years and approaching 100,000 miles, owners are beginning to encounter problems that are unique to the hybrids.

One reader reported to us that in her 2004 Prius the hybrid display began to malfunction and did not work with the result of being unable to get gas into car."

A California reader told us that the monitor is also failing in his Prius and said that Toyota is unwilling to provide any assistance because the monitor is no longer covered by the Toyota warranty.

There is a technical service bulletin out on it from Toyota which tells the dealer how to repair the problem but only if the car is under factory warranty, he said. My car has 49,000 miles on it and is out of warranty.

A Texas Prius owner with 91,000 miles on his hybrid said that "the dashboard lit up with multiple warning lights. The dealer picked it up and said that the transmission went out and it would cost $6,000 to fix and the Prius was out of warranty.

Toyota allowed no coverage, not even partial help even though the transmission was part of the Hybrid Power train covered for 5 years and 100,000 miles.

A southern California Prius owner told us that his car has died on the freeway four times. The second time the dealer had the car for 53 days waiting for parts.

The growing number of complaints and problems owners of aging Prius hybrids are encountering suggest that a wary consumer ought to look long and hard before becoming the second owner of one of these hybrids.

Toyota warrants the hybrid drive system for 100,000 miles, but as Danny in San Antonio discovered, there can be some uncertainty as to which of the Prius components are considered part of the hybrid drive and which are not.

5. Ford Focus

The Ford Focus ignition switch is among the most bitter of lemons facing consumers because its ornery behavior can recur. The switch is known to break again and again ... and sometimes even again. Consumers have complained for years, but Ford is standing firm with its corporate back turned on Focus owners.

Carrie in Grand Haven, Michigan "was stranded at a friend's house until the early hours of the morning."

Joel in Oak Park, Illinois says he has seen it all before. "My 2000 Ford Focus ignition switch has failed and won't turn for the second time in 80,000 miles.

Heather in Wahiawa, Hawaii summed up her problems with her car this way: "My 2000 Focus is a piece of junk. The ignition switched has been replaced three times and is jamming again. Ford continues to insist that I pay for these replacements," she wrote.

Helene was "stranded in a seedy part of town unable to start my car" in Colorado. Dalila and her daughter were stranded in 101-degree heat in the summer while she was pregnant.

The faulty ignition is the most nagging unresolved problem with the Focus. Many Focus consumers have even had a broken ignition repaired under the Ford warranty only to have to replace the locking mechanism themselves once the warranty has expired.

The replacement cost can exceed $500 each time the lock fails -- a lot of money for something that's supposed to be an economy car.

Our advice: When you see a Focus for sale, try to focus on something else.

6. Dodge Durango

The recall of 328,424 Durango SUVs because of the risk of overheating makes the DaimlerChrysler SUV one of the most troubled vehicles for sale in the U.S. today, according to readers of ConsumerAffairs.com.

So it stands to reason that the SUV is no prize on the used market either.

The most recent recall covers 2004 to 2006 model year Durango SUVs, according to Chrysler.

The Durango, which has a base price of $27,055, has now faced 7 recalls in the past year while generating hundreds of complaints from ConsumerAffairs.com readers.

The recalls include incorrect airbag restraint controllers and faulty automatic transmissions that may not be able to shift into "Park."

Anti-lock brake software on the Durango was recalled in 2006. Some of the SUV's rear suspension components were damaged during assembly and became part of a major recall.

The truck was recalled for defective front windshield-wiper motors, malfunctioning turn signals, and headlights as well as windshield wipers.

So far in 2007 ConsumerAffairs.com readers have reported sludge buildup in the motor that required replacement of $1,800 in engine parts and $400.00 in labor and shop supplies to clean the sludge from the engine. Paul in Youngsville, Louisiana says a new engine for his Durango will cost $6,000.

In Jefferson, Maryland Eric did not mince words about his Durango. Oil pressure shoots to zero, ruins engine, out of warranty, 4200 dollars to replace engine.

Larry in Kremmling, Colorado reports that sludge is a problem Durango owners just have to become wary of. "I have close to 200,000 miles and have always had this sludge problem from the very first oil change, he wrote ConsumerAffairs.com.

Sheri paid more than $1,800 to rebuild the transmission in her Durango SUV. Only 15 months later, the transmission has failed again. We are now out more than $2,000 in repairs and cannot afford to get a different vehicle.

Nancy encountered the Durango transmission failure in Port Matilda, Pennsylvania. The transmission has now gone out. Something blew apart in it. I called the Dodge Corp. and they said that there is nothing they can do."

Nancy discovered her transmission failure is just one of many with the Dodge Durango I have done some digging and found out that there have been thousands of these with this problem. Dodge has refused to fix it.

The Durango is not the only Dodge truck with a heavy history of recalls. The Dodge Ram Pickup with a base price of $22,170 was also recalled 7 times in the past year.

On the recall list for the Ram Pickup: faulty anti-lock brake electronic control units, defective front suspensions, airbags that could deploy with excessive force, transfer cases on four-wheel drive models that may inadvertently shift to neutral and cause parked vehicles to roll away, seatbelts that may not be able to secure certain child seats, missing pieces of exterior lighting and defective rearview mirrors.

If shopping for a second-hand SUV, keep on shopping.

7. Ford Taurus
8. Mercury Sable

The old reliable Taurus and its Mercury cousin, the Sable, turn out not to be so reliable after all. Consumers tell us every week of a spring breaking in the car, sometimes shredding a tire.

Here is a typical Taurus story:

My 2002 Ford Taurus is in tip top shape, or so I thought. While driving in a low-speed area my front tire sounded like a gunshot then the car fell to the ground. The mechanic said they cannot believe that this could happen. I had no choice but to replace all my coil springs, because I fear for the safety of my family. There are so many issues with this car yet Ford refuses to help. What can we do?

There may not be much the current owner can do, but if you are looking for a low-price second-hand family sedan, stay away from the Taurus or the Sable.

There are plenty of dull, dependable cars out there. Why settle for something that's dull and undependable?

9. Toyota Engine Sludge

Many older Toyotas have a chronic problem with engine sludge which can cost an unwary second owner thousands of dollars at the hands of a seller unwilling to disclose the sludge problem.

We bought a 2004 Toyota Corolla S new in 2004, a consumer wrote us. I did the oil changes in it up to date, I did not keep the receipts from the oil and oil filter purchase. I recently took it to the dealer because of oil consumption, he said.

I then received a call stating that the engine was full of the jelled oil because I did the oil changes myself.

The Toyota owner can replace the engine which will cost thousands of dollars or attempt to sell the car.

Summary: Be very careful buying a used Toyota. Have the engine examined and the oil tested.

10. General Motors and Dex-Cool

Secondhand General Motors products deserve attention here because ten years after GM began using Dex-Cool as an antifreeze in most of its cars and light trucks, GM car and truck owners continue to complain that the coolant corrodes and clogs radiators and radiator caps, erodes water pumps, rots radiator hoses, causes chronic overheating and engine damage while leading to leaky engine gaskets.

Patricia in Barberton, Ohio, feels cheated by the automaker. "I have had 2 intake gaskets replaced on my 1997 Pontiac Grand Am. The gaskets cost me close to $1,000 and they told me there is no guarantee it won't happen again," she wrote in a complaint to ConsumerAffairs.com.

"I just recently saw about the Dex-Cool problems and that is what I have been using in my vehicle since that is the kind that is required from the automakers," Patricia said.

Dex-Cool is now used in almost 40 million vehicles sold by GM since 1996. On its web site, GM claims Dex-Cool will last 5 years or 150,000 miles but a steady stream of consumers insist the product is defective and has damaged their vehicles.

That did not work for Rob in Mount Laurel, New Jersey. My 2001 Malibu with 35,000 miles needs a intake manifold gasket replacement. In addition, my 2001 Olds Aurora with 52,000 miles also has leaking gaskets GM should be responsible for these repairs since they are all Dex-Cool related, he said.

Consumers looking at used General Motors vehicles should pay additional attention to the engine and have an trusted mechanic examine the cooling systems and engine gaskets.

Good Hunting

While this list is far from exhaustive, it hits the trouble spots we've heard most about. Of course, all used cars are potential trouble. If you can swing it, it's better to buy a new model, even if you get one that's stripped down. With gas prices higher than ever, most of us would be better off with a small four-cylinder sedan, preferably with a manual transmission.

One last word of caution: While the Internet is a valuable place to research cars, it's a terrible place to buy them. You should only buy a car you have examined in person. Ideally, you should take it to an experienced mechanic for a complete inspection. Whatever you do, never buy a car sight unseen on the Web. You're likely to get a flood car, or something even worse.