We've updated our reliability stats for the A4 / S4 to include owner experiences through June 30, 2014.

Repair frequencies, in terms of repair trips per 100 cars per year:

2005 A4: 90, moderate, small sample size
2005 S4: 64, moderate, small sample size
2004 A4: 90, moderate
2004 S4: 94, moderate, small sample size
2003 A4: 42, low
2002 A4: 151, high

We'll have further updates in August and in November. The more owners participate, the more comprehensive and precise these will be.

To see how competitors compare, and to sign up to help improve this information:

Audi A4 / S4 reliability ratings and comparisons

 

We've updated our reliability stats for the A4 / S4 to include owner experiences through September 30, 2014.

Repair frequencies, in terms of repair trips per 100 cars per year:

2005 A4: 78, moderate, small sample size
2005 S4: 65, moderate, small sample size
2004 A4: 115, high
2004 S4: 87, moderate, small sample size
2003 A4: 76, low, small sample size
2002 A4: 202, high

Additional participants always helpful (especially if you see "small sample size" next to the year, or no stat at all).

To view the repairs behind these numbers, check the stats for other cars, and sign up to help improve this information (next update in February):

Audi A4 / S4 reliability ratings and comparisons

 

We've updated our reliability stats for the A4 / S4 to include owner experiences through the end of 2014.

Repair frequencies, in terms of repair trips per 100 cars per year:

2005 A4: 100, high, small sample size
2005 S4: 57, low, small sample size
2004 A4: 115, high
2004 S4: 77, moderate, small sample size
2003 A4: 89, moderate, small sample size
2002 A4: 160, high

We'll have further updates in May and in August. The more owners participate, the more comprehensive and precise these will be.

For the details, including how competitors compare, and to sign up to help improve this information:

Audi A4 / S4 reliability ratings and comparisons

 

So, how have these cars been doing lately?

Our reliability stats for the A4 / S4 now include owner experiences through March 31, 2015. (Others are nearly a year behind.)

In terms of repair trips per 100 cars per year ("low" is best):

2005 A4: 66, low, small sample size
2005 S4: 59, low, small sample size
2004 A4: 127, high
2004 S4: 74, low, small sample size
2003 A4: 109, moderate, small sample size
2002 A4: 147, high

Next updates in August and in November. More of our members have been buying than selling these, so the sample sizes have been shrinking. I hope some people here can help reverse this trend

For repair descriptions, the stats for other cars, and to sign up to help improve this information:

Audi A4 / S4 reliability

 

Our reliability stats for the A4 / S4 now cover the year ending June 30, 2015. (Others are over a year behind, and so report how these cars were doing when a year younger.)

Repair trips per 100 cars:

2005 A4: 86, moderate, small sample size
2005 S4: 73, moderate, small sample size
2004 A4: 121, high, small sample size
2004 S4: 56, low, small sample size
2003 A4: 92, moderate, small sample size
2002 A4: 122, high

For the descriptions of all reported repairs, results for other models, and to sign up to help improve this information:

Audi A4 / S4 reliability ratings and comparisons

 

We've updated our reliability stats for the A4 / S4 to include owner experiences through September 30, 2015.

Repair frequencies, in terms of repair trips per 100 cars per year:

2005 A4: 82, moderate, small sample size
2005 S4: 75, moderate, small sample size
2004 A4: 109, moderate, small sample size
2004 S4: 45, low, very small sample size
2003 A4: 85, moderate, small sample size
2002 A4: 108, moderate

We'll have further updates in February and in May. The more owners participate, the more comprehensive and precise these will be.

For the details, including repair descriptions, and to sign up to help improve this information:

Audi A4 / S4 reliability ratings and comparisons

 

We've updated our reliability stats for the A4 / S4 to include owner experiences through the end of 2015, about eight months ahead of other sources. In terms of repair trips per 100 cars per year--lower is better:

2005 A4: 83, moderate, small sample size
2005 S4: 93, moderate, small sample size
2004 A4: 128, high, small sample size
2004 S4: 63, low, very small sample size
2003 A4: 109, moderate, small sample size
2002 A4: 105, moderate

As seen in the sample size notes, more participants would be very helpful for this generation of the A4.

For the repairs behind these stats, reliability information on other models, and to sign up to help improve this information:

Audi A4 / S4 reliability ratings and comparisons

 

We've updated our reliability stats for the A4 / S4 to include owner experiences through June 30, 2016. Reliability information elsewhere is based on a survey conducted in April 2015--well over a year ago.

Repair frequencies, in terms of repair trips per 100 cars per year:

2005 A4: 119, high, small sample size
2005 S4: 47, low, very small sample size
2004 A4: 117, moderate, small sample size
2004 S4: 91, moderate, very small sample size
2003 A4: 101, moderate
2002 A4: 96, moderate

Given the small sample sizes, additional participants would be very helpful.

For the repairs behind these stats, reliability information on other models, and to sign up to help improve this information:

Audi A4 / S4 reliability ratings and comparisons

 

We've updated our reliability stats for the A4 / S4 to include owner experiences through September 30, 2016.

Repair frequencies, in terms of repair trips per 100 cars per year (lower is better):

2005 A4: 170, high, very small sample size
2005 S4: 75, moderate, very small sample size
2004 A4: 120, high, small sample size
2004 S4: 89, moderate, very small sample size
2003 A4: 103, moderate
2002 A4: 104, moderate, small sample size

Additional participants always helpful.

For the repairs behind these stats, reliability information on other models, and to sign up to help improve this information:

Audi A4 / S4 reliability ratings and comparisons