FOUNTAIN VALLEY, Calif. -

Despite recent production struggles related to natural disasters in both Japan and Thailand, Asian OEMs still top the list when it comes to reliability and “vehicle health”, according to CarMD.com.

In its first-ever CarMD Vehicle Health Index, Toyota came out on top and Hyundai and  Honda following closely behind in the index that rank manufacturers and vehicles using real world, statistically-based data on "check engine"-related failures and repair costs.

"CarMD understands that when you’re shopping for one of the most expensive purchases in life — your car — it’s important to be armed with data to help you make the best possible decision based on the reliability of that vehicle," said Art Jacobsen, vice president of CarMD, 

"We are releasing this data to give car and truck buyers a completely unbiased, data-driven view and never-before-seen level of transparency into the vehicles they may be considering and recognize the manufacturers that continue to make progress by lowering cost of ownership and designing vehicles to last longer,” he continued.

The Index ranking is based on the combined fewest average repair incidents and lowest average repair costs for model year 2001 to 2011 vehicles in the U.S. from Oct. 1, 2010 through Oct. 1 of this year, company officials explained.

And on top of gauging the “healthiest” manufacturers, the index also ranks the top 100 vehicles, the top three vehicles by category and most common problems by make.

The "Healthiest" Manufacturers

Delving deeper into which manufacturers had the fewest problems, Toyota came out as  the No. 1 ranked automaker in the U.S., based on a ranking derived from the fewest percentage of "check engine" light-related related problems and lowest average repair cost.

Based on a system in which the lower the rating, the better the overall ranking, Toyota took home the lowest Index rating of 0.67 percent.

Rounding out the top five vehicle manufacturers of 2011 are Hyundai (0.85 percent), Honda (0.89 pecent), Ford (0.95 percent) and General Motors (0.97 percent), respectively.

CarsMD also offered the following chart, highlighting the results in greater detail:

 Vehicles that Topped the List

Moving onto highlight the top ranked, “healthiest” vehicles, Honda and Toyota also came out on top in this category, each taking four of the top 10 ranked vehicle spots.

The 2009 Toyota Corolla ranked No. 1 and had the lowest combined repair incidents and lowest average repair costs per number of registered vehicles with a CarMD Index rating of 0.085.

Toyota also touted the 2009 Toyota RAV4 in the No. 5 spot, as well as the 2009 Toyota Camry (No. 7) and 2008 Toyota Highlander (No. 10).

For Honda, its top ranked vehicles included the 2008 Honda CR-V (No. 2), 2007 Honda CR-V (No. 3), 2009 Honda Accord (No.  4) and 2009 Honda Pilot (No. 8).

The 2011 Hyundai Sonata came in sixth place, and for the only domestic unit that made the cut, the 2005 Chevrolet Blazer came in ninth; rounding out  the top 10 highest ranked vehicles on the road in the U.S. since 2001, according to CarMD.

Most Common Repairs

After choosing the "healthiest"  manufacturers and vehicles, CarMD also delved into the most common repairs by brand and make, further explaining the reasoning behind their ratings.

“Different vehicle makes tend to have a unique set of problems and common failures. The CarMD Index helps point out common problems by manufacturer, which is important for car owners to recognize in their maintenance and repair routines,” company officials explained.

Interestingly, according to the CarMD Vehicle Health Index, the most common engine repair light seen on vehicles in the U.S. is the "replace oxygen sensor."

Even the Toyota vehicles seem to have this problem, officials said.

The company found that the most common culprit is a faulty O2 sensor, accounting for about 15 percent of Toyota’s check engine repairs over the past year.

Additionally, Suzuki’s oxygen sensor also had problems, with 27 percent of its check engine repairs over the past year due to this issue.

Highlighting the issue in greater detail, the O2 sensors measure the amount of unburned oxygen in the exhaust and tell a car’s computer when there is either too much, or not enough fuel as compared with oxygen for ideal operation, the company explained.

If a faulty O2 sensor is not repaired, the car’s gas mileage can drop by as much as 40 percent, officials surmised.

Breaking the repair cost down, the average cost to replace an O2 sensor is $238.71in the U.S. This number is in comparison to as much as $700/year in wasted fuel if the problem is not fixed.

Other frequent repairs which came to light were Mercedes’ Mass Air Flow Sensor issues and Lincoln’s tendency to experience ignition coil and spark plug-related issues.

Wrapping up the study results, Jacobsen commented on the potential perks of the new Index: "As a result of compiling the industry’s first and most comprehensive database of diagnostic trouble codes and repairs for ‘check engine’-related problems, CarMD is uniquely positioned to provide actual data on a wide range of vehicles and manufacturers.

"Sourced directly from a nationwide network of automotive technicians and vehicle owners since 1996, our Index takes a never-before-seen approach to ranking vehicles based on total vehicle population, making it possible to compare a 10-year-old vehicle with a newer one,” he continued.

“This is particularly important since drivers are holding onto vehicles longer than ever before with an average age in excess of 10 years. We believe this data will help consumers and the industry identify important trends and further the age-old debate on whether to buy new versus used," Jacobsen concluded.