TrueDelta reports absolute repair rates that make the differences between cars much clearer. Results are updated four times a year, to track cars closely as they age.

Among Mercedes, we currently provide results for the C, E, and GL. No year of the S-Class is included in the survey yet. For a model year to be included, at least 25 owners have to sign up to participate.

Participants simply report repairs the month after they occur on a one-page survey. When there are no repairs, they simply report an approximate odometer reading four times a year, at the end of each quarter.

To encourage participation, participants receive full access to all results, not just those for the S-Class, free of charge.

For the details, and to sign up to help out:

Car reliability research

 

63 S-Class owners signed up so far. A good start, but more will be needed to cover all model years from 1995 on.

Help get your year included, so we can start reporting results back to the forum:

Auto reliability research

 

And now 97 owners signed up, vs. 101 for the 7-Series. The 2000 and 2007 are both well over halfway to the minimum sample size.

Help get your year included:

Car reliability research

 

I've added my 1997 S Class, though can sum it up here in terms of reliability, never boken down, never needed any work outside the usual 10k services, except a new rear view mirror (and the usual tires ever x miles etc).

Could you confim what you mean by "20 repair trips per 100 cars" in the notes, or the results. Is this saying that for ever 100 cars 20 have reported that they have had to have repairs? Or is saying for every year, select 100 cars and 20 of them will have needed to have repairs done? Sorry I think I am being slow today.....

 

It's the last. If you selected 100 cars, over the past year they will have required 20 repair trips (some with multiple repairs) between them. Some cars are in the shop more than once, so the number of cars with zero repairs would actually be over 80 with this stat.

I've been planning to also provide a second stat that gets more at what you're saying: the percentage of cars that required no repairs in the past year. And another that would be the percentage requiring 3+ repairs--but need a larger sample size for these, especially the latter.

To help make this possible:

Car reliability research

 

The 2007 has been added to the survey, the first large premium sedan to make it. Thanks, guys.

Other years are getting close.

For the details, and to sign up to help make this happen (if you haven't already):

Car reliability research

 

129 S-Class owners plus another 13 for the CL now signed up. A good start, but more are needed to provide reliability stats for all model years from 1995 on.

Not yet signed up? Details here:

Car reliability research

 

Results recently updated for the C, E, GLK, and GL. Hoping to have an initial result for the S-Class with the next update, in May. We might still be a couple responses short, so additional participants would be very helpful.

 

We might have some results for the 2007 in August, but it's going to be close. Even a few additional participants would be very helpful.

The 2000 is only five cars short of the minimum, and the 2001 is now 2/3 of the way.

Help get your year included:

Car reliability research

 

We have an initial result for the W221 S-Class based on owner experiences through June 30, 2010. With a reported repair frequency of 154 repair trips per 100 cars per year, the 2007 is worse than average.

This is based on a very small sample size.

We'll have further updated in November and February. With more participants, we could provide more precise results and cover more model years.

For more detailed results, and to sign up to help:

Mercedes-Benz S-Class reliability comparisons