Reliability: Honda Civic vs. Volkswagen Jetta

The reliabilities of all model years of the Honda Civic and the Volkswagen Jetta can be measured using the PPMY index which is defined as problems reported per thousand vehicles per Year:

    PPMY = P / S / Y * 1000,

where P = total problems reported during the life of a particular model year; S = total units sold of the model year; Y = years since the model year has been on the market (the age of the vehicle). The index can also be written as:

    PPMY = [Problems / (Sales/1000)] / Age.

A bigger PPMY index indicates less reliability of the given model year cars. For example, the most problematic model year of the Honda Civic is the 2016 Honda Civic. This model had a total of 351,522 cars sold in the United States and had 297 problems reported as of today. The PPMY index can be calculated as:

    PPMY = [Problems / (Sales/1000)] / Age = [297 / (351,522/1000)] / 2 = 0.42.

Similarly, the most problematic model year of the Volkswagen Jetta is the 2010 Volkswagen Jetta. It had a total of 70,202 cars sold in the United States and had 891 problems reported as of today. The PPMY index of this model can be calculated as:

    PPMY = [Problems / (Sales/1000)] / Age = [891 / (70,202/1000)] / 8 = 1.59.

The complete results for the recent model years of Honda Civic and Volkswagen Jetta are shown in Table 1 and Table 2, respectively.

To study the aggregated reliabilities of the Honda Civic and Volkswagen Jetta vehicles, we use the PPM index which is defined as:

    PPM = Total Problems / (Total Sales/1000),

Where the total problems in the equation is the total number of problems reported for all model years listed in Table 1 (Honda Civic, 2002 to 2017) and Table 2 (Volkswagen Jetta, 2002 to 2017); The total sales in the equation is the the total number of vehicles sold in the United States for all model years in Table 1 and Table 2. The results are shown in Table 3.

Honda Civic Problems

Volkswagen Jetta Problems