Audi A3 owners have reported a total of 519 problems for their cars built in the
15 model years
listed in the chart below.
The chart shows the number of problems reported across all service years for each given model year of the Audi A3.
The 2006 Audi A3 cars have the most problems reported (126 problems).

Table 1. Total number of problems by model year for Audi A3

The following chart shows the 22 most common problems for Audi A3 cars.
The number one most common problem is related to the vehicle's air bags
(201 problems).
The second most common problem is related to the vehicle's power train (90 problems).

Compare Reliability Across Model Years Using PPMY Index

It would not be fair to compare the Audi A3 of an older model year to newer model years
since older vehicles have been in service longer and thus are expected to have more problems.
In order to compare the reliability across A3 model years, we use the PPMY index which is defined as the
problems reported per thousand vehicles per Year.
A smaller PPMY index indicates greater reliability of the given model year cars.

PPMY = P / S / Y * 1000,

where P = total problems reported during the life of a Audi A3 model year;
S = total units sold of the model year; Y = years since the debut of the model year (the age of the vehicle).

The results are shown in Table 3.

Table 3. Use PPMY Index to Compare Reliability Across A3 Model Years

Another way to measure the reliability across the model years of the Audi A3
is to use the total number of problems reported during the vehicle's first year in service, as shown in the Table 4.

Table 4. Number of problems in vehicle's; first service year