In our research we use the PPMY index to compare the reliability of vehicles. The PPMY index of a certain model is defined as the problems reported per thousand vehicles per Year. The total sales of the 2018 BMW M3 in the United States are 5,854 units [1]. If the total number of problems reported by BMW M3 owners in the last 1 years is 1, and the age of the vehicle is 1, the PPMY index can then be calculated as

The following chart shows the number of problems reported during each of the service
years since the debut of the 2018 BMW M3 in 2018.

Table 2. PPMY Index and Problem Occurrence Trend

Service Year

Number of Problems

2019

1

2018

0

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Compare the 2018 BMW M3 with Other Model Years

When making the decision between buying a new or used BMW M3,
the following table can be used to compare the 2018 BMW M3
with the BMW M3 from other model years.
Note that the number of problems reported for the 2018 M3 is 1
while the average number of problems reported for the 18 model years of the BMW M3 is 23.

Table 3. Compare the 2018 BMW M3 with other model years