American cars versus Japanese cars - a reliability study

In this article, we study the reliability of American and Japanese cars by comparing the trend of problem occurrence across the production years. The American car brands selected in this study are Cadillac, Chevrolet, Chrysler, Dodge, Ford, GMC, Jeep, and Lincoln. The Japanese brands selected are Acura, Honda, Infiniti, Lexus, Mazda, Mitsubishi, Nissan, Subaru, Suzuki, and Toyota. Figure 1 shows the total number of problems reported for cars built from 1996 to 2013 for these American and Japanese brands.

Figure 1. Total Number of problems reported for 8 American and 10 Japanese brands

  • Model year 1996, Number of problems: 27979
  • Model year 1997, Number of problems: 29289
  • Model year 1998, Number of problems: 30393
  • Model year 1999, Number of problems: 37346
  • Model year 2000, Number of problems: 41431
  • Model year 2001, Number of problems: 36396
  • Model year 2002, Number of problems: 39322
  • Model year 2003, Number of problems: 35342
  • Model year 2004, Number of problems: 39261
  • Model year 2005, Number of problems: 43311
  • Model year 2006, Number of problems: 37739
  • Model year 2007, Number of problems: 32159
  • Model year 2008, Number of problems: 22622
  • Model year 2009, Number of problems: 12930
  • Model year 2010, Number of problems: 16164
  • Model year 2011, Number of problems: 8789
  • Model year 2012, Number of problems: 5826
  • Model year 2013, Number of problems: 4196
  • Model year 2014, Number of problems: 1108


Compare reliability using The Annual Problem Occurrence Index (APO Index)

Notice that in Figure 1 the newer vehicles tend to have fewer problems reported. This is because the newer cars have been in service for a shorter time. In order to better compare the reliability of the vehicles across production years, we use the annual problem occurrence index (APO Index). The annual problem occurrence index is defined as the total number of problems of all cars built in a particular year divided by the number of service years. The result is then normalized to 100. Figure 2 shows the annual problem occurrence index (APO Index) for all of the eight American brands and ten Japanese brands. Notice from Figure 2 that there was a large spike of problems for 2010 model year cars.

Figure 2. The annual problem occurrence index of 8 American and 10 Japanese brands

  • APO Index of all 1996 American and Japanese cars: 32
  • APO Index of all 1997 American and Japanese cars: 35
  • APO Index of all 1998 American and Japanese cars: 39
  • APO Index of all 1999 American and Japanese cars: 51
  • APO Index of all 2000 American and Japanese cars: 61
  • APO Index of all 2001 American and Japanese cars: 58
  • APO Index of all 2002 American and Japanese cars: 68
  • APO Index of all 2003 American and Japanese cars: 66
  • APO Index of all 2004 American and Japanese cars: 81
  • APO Index of all 2005 American and Japanese cars: 100
  • APO Index of all 2006 American and Japanese cars: 98
  • APO Index of all 2007 American and Japanese cars: 95
  • APO Index of all 2008 American and Japanese cars: 78
  • APO Index of all 2009 American and Japanese cars: 53
  • APO Index of all 2010 American and Japanese cars: 83
  • APO Index of all 2011 American and Japanese cars: 60
  • APO Index of all 2012 American and Japanese cars: 60
  • APO Index of all 2013 American and Japanese cars: 87


Figure 3 shows the annual problem occurrence index (APO Index) of the eight American brands. Notice from Figure 3 that the reliability of American cars has improved steadily since 2005.

Figure 3. The annual problem occurrence index of 8 American car brands

  • APO Index of 1996 American cars: 42
  • APO Index of 1997 American cars: 46
  • APO Index of 1998 American cars: 48
  • APO Index of 1999 American cars: 66
  • APO Index of 2000 American cars: 74
  • APO Index of 2001 American cars: 65
  • APO Index of 2002 American cars: 73
  • APO Index of 2003 American cars: 63
  • APO Index of 2004 American cars: 76
  • APO Index of 2005 American cars: 100
  • APO Index of 2006 American cars: 94
  • APO Index of 2007 American cars: 81
  • APO Index of 2008 American cars: 69
  • APO Index of 2009 American cars: 43
  • APO Index of 2010 American cars: 79
  • APO Index of 2011 American cars: 72
  • APO Index of 2012 American cars: 66
  • APO Index of 2013 American cars: 74


Figure 4 shows the annual problem occurrence index (APO Index) of the ten Japanese brands. Notice from Figure 4 that the reliability of Japanese cars has improved slightly from 2005 to 2009. In 2010 however, Japanese cars experienced a big setback in reliability. The problems reported that year reached the highest in history. It was not a coincidence that in 2010 Toyota, Honda, and other Japanese automakers announced massive recalls for millions of their vehicles sold in America.

Figure 4. The annual problem occurrence index of 10 Japanese car brands

  • APO Index of 1996 Japanese cars: 32
  • APO Index of 1997 Japanese cars: 35
  • APO Index of 1998 Japanese cars: 39
  • APO Index of 1999 Japanese cars: 51
  • APO Index of 2000 Japanese cars: 61
  • APO Index of 2001 Japanese cars: 58
  • APO Index of 2002 Japanese cars: 68
  • APO Index of 2003 Japanese cars: 66
  • APO Index of 2004 Japanese cars: 81
  • APO Index of 2005 Japanese cars: 100
  • APO Index of 2006 Japanese cars: 98
  • APO Index of 2007 Japanese cars: 95
  • APO Index of 2008 Japanese cars: 78
  • APO Index of 2009 Japanese cars: 53
  • APO Index of 2010 Japanese cars: 83
  • APO Index of 2011 Japanese cars: 60
  • APO Index of 2012 Japanese cars: 60
  • APO Index of 2013 Japanese cars: 87