In late 2005 I started conducting my own reliability research. I'm reporting absolute stats like "times in the shop" that will make the differences between cars much clearer. I’ll also be updating results four times a year, so there will be information on new models sooner.

There's plenty of discussion about how the reliability of BMWs compares to that of other cars. But there aren't any good numbers out there to enable a precise comparison. I hope to fix this.

With over 700 owners signed up, I've been providing results for every year from 1999 on for the 3-Series. But fewer 5-Series owners have signed up, so we're only providing results for the 2008 so far. As I update this post, other recent years are only two to six owners short of the minimum. Real close.

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, panel members will receive full access to the results for free.

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

Auto reliability research (http://www.truedelta.com/reliability.php)

you probably want rather new cars, huh? :rolleyes

Not new, but newer. (I see you have a 1988.) Currently I plan to go back ten model years.

A number of people have asked me to collect data on even older cars. The problem, I'm assuming, is that the older cars get the more reliability becomes a function of how the car was maintained and driven rather than the initial engineering.

But since this is an assumption--no actual data--I'm going to see how the data on the 1998s and 1999s look. If these data seem reasonably valid I might go back a few more years. 1988 isn't likely, though.

Do you have criteria that much be meet in order to participate? That is, miles per year, I6 or v8 etc. I no staticians, but I quite sure driving habits will making the data less than useful.

No criteria of that sort. I collect odometer readings quarterly, so it'll be possible to track reliability by mileage as well as time.

Frankly, most of the problems I see have little to do with driviing habits. I do intend to eventually break down results by powertrain, but this will require a very large sample because engine problems are very rare in the first 100,000 miles with just about any car.

Latest results recently posted here for other models:

TrueDelta Vehicle Reliability Survey results (http://www.truedelta.com/results0307.php)

With enough participants, I'll be able to include the 5er in future results. Currently 82 owners are signed up for all model years, including 10 2003s.

Now 112 signed up.

I'm going to start collecting data on the 2008 this month, since ten owners have already signed up and its early in the model year. Will need more participants to provide results, but I'm going to forecast that they'll come.

Many other years remain about halfway to the minimum. The situation is similar with the E-Class, except they don't have a new turbo six to get buyers all excited about the 2008:)

For more information, and to sign up to help out:

Vehicle reliability research (http://www.truedelta.com/reliability.php)

mkaresh, nice project, btw. I've always been a fan of bimmers but have been a little leery of the reliability issues, though. At least BMWs don't have the issues that Benzes have. I've always been curious to know exactly what kind of problems Bimmers do have. One of my friends, a former owner, says that it's a hit-or-miss with owning a reliable/trouble-prone BMW.

Perhaps you should talk to my orthodontist. He leased his new '07 550i last August and for the first 3 months he's had it, 2 of them were spent at the BMW dealer. He had electrical and iDrive issues. One of them involved his swiveling headlamps. Since he lives up a hill, he noticed that one of the headlamps wouldn't swivel back straight. Needless to say, coming from Lexus, he was pretty peeved to be paying for a 550i lease and being stuck with an el-cheapo, albeit BMW-paid, Enterprise Ford minivan.

Doubt he's on the forums, though.

Thinking about buying one.
My only concern is the miles on it. It has 180,000. What type of engine life can I expect?

At that mileage, I suspect a lot will depend on how well the engine was maintained and whether it did a lot of short trips or lots of highway miles.

As mentioned earlier, data collection has started on the 2008, but I'll need more participants before a result can be posted.

The latest results ended up including 73 models, including a few years of the 3.

Total number of 5-Series owners signed up to help out now 141, but need more for all model years.

Auto reliability research -- need more 5ers! (http://www.truedelta.com/reliability.php)

hmm so i just enroll at panel enrollment right?

Thanks for asking.

Yes. I make it a little harder than it has to be because I want people to know what they're signing up for. So I always link to the page that describes the research, and there are three links to the enrollment form on that page (top, bottom, box at top right).

i think theyr pretty reliable...

Posted that result. About average, which is good for a complex luxury car.

Updated result for the 2008 in May.

Other model years aren't yet included in the survey. Many are about 2/3 of the way to the minimum. Need more participants.

For the details, and to help get your model year included:

Vehicle reliability research (http://www.truedelta.com/reliability.php)

There will an updated result for the 2008 later this week.

For other recent years, we're 2/3 to 3/4 of the way to the minimum for all of them.

Help get your year included in future results:

Vehicle reliability research (http://www.truedelta.com/reliability.php)

Posted that result. After removing a duplicate vehicle, we ended up a single response short of the minimum, so the result is asterisked.

Even so, it appears that the repair rate for the 2008 5er is better than the average, maybe even much better. I have noted that BMWs often do well in their first year, though, then require an average number of repairs in later years.

For the full set of results, and sign up to help (if you haven't already):

TrueDelta Vehicle Reliability Survey results (http://www.truedelta.com/latest_results.php)

so when you say in the shop do you also include prevention work?

for example... one of the first things i did when i bought my car was changing out the drive belts and will be working on the cooling system later this month.

in my short time as owner my car hasn't broken down or needed to go to the shop.... But I am working so that it never has to.

would something like this count for the survey?

Belts are considered a wear item and are not reportable as repairs.

Preventative maintenance is generally excluded.

The main survey measures repair trips, when something has broken and needs fixing.

Now 270 5-Series owners signed up--we've come quite a long way.

The current counts--with 25 the minimum sample size:
2009: 2
2008: 46
2007: 20
2006: 21
2005: 23
2004: 23
2003: 25
2002: 19
2001: 20
2000: < 18
1999: < 18
1998: 21

So nearly every recent model year is close to the minimum. Next February we could have results for all of these if owners keep signing up like they have been.

Vehicle reliability research (http://www.truedelta.com/reliability.php)

284 now, and around the minimum for every year from 2001 through 2007.

A few more participants per year could make a big difference.

Vehicle reliability research (http://www.truedelta.com/reliability.php)