9 popular used cars with dubious reliability

You did everything right when buying your car: Consumer Reports, enthusiast magazines, the big automotive online sites. You even went through the trouble of visiting enthusiast forums that specialized in the exact same car that ended up on your driveway.

So how did you wind up on a first-name basis with your mechanic? This happens more than you might think. Most car buyers will spend anywhere from weeks to several months trying to find a nice daily driver — only to find out that their cherished chariot has turned out to be as rough as a worn-out mop.

New? Used? It doesn't matter. Over time, quality always manages to reveal itself. The tough part for you is that most automotive publications will only test the new stuff, and most quality studies are only focused on first owners and short-term results.

Manufacturers use all of these sources as marketing tools, and some of the most popularized studies are not sound indicators of durability. Long-term reliability studies do a far better job, but they also have an Achilles' heel: Most of them are either captive to their subscribers, or only have the means to survey first owners. This creates a more challenging issue called ownership bias.

Plenty of us have ridden in cars that were barely hanging on for their dear mechanical life thanks to an owner who just didn't know anything about cars. Neglect, abuse, wear issues, and the owner's rose-colored glasses manage to make these surveys flawed.

That's why we decided to do something different: Measure failure. Specifically, nearly 450,000 cases of it. We co-developed a study that focuses on the exact point where the owner says, "No more!" — when they're willing to just throw up their hands and trade in that retail product for a cheap wholesale price.

All of these vehicles were independently inspected and appraised by professional car buyers who are trained to detect mechanical and structural issues, which can be overlooked or unreported by the owners in other industry studies, and are recorded by those who have no owner bias.

What we discovered is that many of the most popular vehicles in today's used-car market have severe long-term reliability issues when it comes to specific powertrains. One engine and transmission combination may do an outstanding job, while another may be truly abysmal.

Which popular cars have specific reliability issues? Here are several surprises.

Honda Accord: The Accord carries a stiff price premium in today's used car market due in large part due to its reputation for reliability. Yet, the flies in the ointment are automatic transmissions for their older six-cylinder models. Honda recalled over a million vehicles way back in 2004. However, there are reports that transmission issues for those recall vehicles still persist, and our survey shows that this issue remains chronic enough to make the Honda Accord just below average in terms of long-term reliability.  

Nissan Altima: Nissan Altimas with four-cylinder engines built between 2002 and 2006 experienced excessive oil consumption as a result of improper performance of the piston rings. Catalytic converters on these models also tend to break down during this same period, which scores the cylinder walls of the engine.

Mini Cooper: The Mini Cooper is one of the ten worst vehicles in our survey due to improper shifting of their continuously variable transmissions for the 2002 thru 2006 Mini Cooper and the 2005 thru 2008 Mini Convertible. BMW has recently settled a class action lawsuit, but our survey shows that this issue remains chronic for traded-in vehicles around the country during the last two years.