So Does Toyota Really Have a Quality Issue?-Lean Six Sigma Perspective

Toyota, Lean Six Sigma

Toyota, Lean Six Sigma

Whenever I write about continuous improvement and lean Six Sigma without fail I get a comment about Toyota and its quality issues.  So I decided to investigate this matter further and present the facts and let the data be the voice of reason.  I do expect the proverbial “Yabut and Costello” comments i.e. BUT what about this and what about that; however, my goal is to compare trends over time and across the automotive industry.

In summary, Toyota’s quality issues are far less severe, than what we are lead to believe, when compared to the other automobile manufacturers. However, from a Lean Six Sigma perspective, there is much work to be done and, here is the data to demonstrate this.


1) 2011 Initial Quality Study

We will start by looking at a comprehensive survey conducted in 2011 called the Initial Quality Study (IQS).  IQS looks at the problem owners have reported during the first 90 days of owning a car. Participants of the study were asked to select from 228 potential problems with their vehicles from major malfunction to problems understanding controls.  The results of that study are presented in the graph below and the values were obtained from (

Lean Six Sigma, Top 10 problems per 100 vehicles

Source: 2011 Initial Quality Study 2011 (


The graph shows, the problems per 100 vehicles (for the top 10 vehicles, i.e. those with the lowest problems per 100 vehicles) . A problem may include problems in assembly or design even if the design was built according to specifications.  According to the graph and the 2011 IQS survey, out of the top 10 brands with the least problems per 100 vehicles, Lexus had 73 problems per 100 vehicles while GMC had 103.  Not shown in the graph but interestingly enough is that Ford had 7th highest number of problems per 100 vehicles at 117.

Toyota, although not faring the best, does have one of the best records with respect to problems per 100 vehicles among over 20 vehicles included in the 2011 IQS survey. 


2) Trend in Initial Quality Study

In the 2012 IQS survey (, Lexus ranked the best car with respect to the lowest number of problems per 100 vehicles for a second year in row with 73 problems per 100 vehicles.  In addition, Honda was once again ranked in the top 5 with respect to the lowest number of problems per 100 vehicles.

Jaguar, Porsche, Cadillac, Honda and Infinity had substantial improvements in the number of problems per 100 vehicles (20 to 50% improvement).  Note that a positive percentage increase means an improvement, i.e. the number of problems per 100 vehicles declined.   

For Toyota, the problems per 100 vehicles stays within the top 10 and the improvement from the year before was 12% which is much higher than the Industry average improvement of 5%.


Concluding Thoughts

Although more years of data is required to see for certain if the quality trends observed in 2011 and 2012 are likely to continue, for now Toyota does seem to have better than average quality ratings relative to the overall automobile industry.  

That being said from a lean six sigma point of view, 88 defects per 100 vehicles is less than desirable. The goal for six sigma is 3.4 defects per million, which is drastically different than what Toyota is achieving today.  In other words, Toyota has much to improve on its quality relative to the Lean Six Sigma standards.

Perhaps it is time for Toyota and other car manufactures to focus more on six sigma (i.e. focus on quality) and less on Lean (i.e. focus on time).  What do you think?