mkaresh

I wanted more up-to-date car reliability information that included actual repair rates. So in late 2005 I started getting people together to make this possible. TrueDelta now updates actual repair frequencies, not just dots, four times a year, to report on new models sooner then track cars closely as they age.

With 350 owners signed up to participate so far, we've started providing reliability stats for the Boxster and Cayman. But more participants remain needed to fully cover all model years. So I'm grateful to this forum for giving me permission to post about the survey here.

To encourage participation, participants receive full access to all results, not just those for the Boxster, for free. I'll share results, once we have them, in this thread after each update.

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

Car reliability research

mkaresh

We have updated reliability stats for the Boxster and Cayman that include owner experiences through December 31, 2009. In terms of repair trips per 100 cars per year:

2003: 125, small sample size

2002: 167, small sample size

2001: 125

2000: 129

1999: 133

With more data this time around, we're seeing more consistent results from year to year. Only the 2002 doesn't fit with the others.

The 2002 and 2003, both with small sample sizes, are worse than average. The other years, including those with decent sample sizes, are about average.

I'd like to report specifically on the IMS failure rate, but we will need more participants to do this. So far only a couple of IMS failures have been reported.

We'll have further updates, possibly including additional model years depending on the number of participants, in May and August.

Porsche Boxster reliability comparisons

LVDell

Is this some sort of joke?

mkaresh

Pretty sure it's not a joke.

Perhaps you missed the "per 100 cars" bit, and read the stats as 120+ repairs per car?

LVDell

So you have access to the PCNA database or just going off voluntary self report data?

mkaresh

Voluntary self-report data, collected going forward (rather than retrospective) to greatly reduce any bias from self-selection. Main limitation is sample sizes, but these have been growing.

LVDell

Hate to break it to you but sample size is NOT your limitation.

mkaresh

Not the first time I've had the discussion you're starting. My background in survey research includes a Ph.D. from the University of Chicago and work at the National Opinion Research Center.

The things you think are problems aren't really significant problems. The methods and metrics I'm using were designed to deal with them. This is not your typical Internet-based survey.

LVDell

Then I'd love to hear the metrics you are using. FYI....My background is in survey and scale development in my Masters and research design and statistics in my Ph.D.

I can think of many flaws so if you claim they aren't significant then I'd be interested to hear how you cleared that hurdle.

Carreralicious

M96 based engines are in the 996 Carrera models too. Are you gathering data on these cars as well?

mkaresh

There's more to a car than an engine.

Not enough 911s signed up yet to include them in the survey. Hopefully soon.

JoeFromPA

LVDell - I realize I just joined on here (posted in another sub-forum some information I was seeking). I've known Michael (on the internet) for ~4-5 years now, from his reviews on epinions.com, his reviews for thetruthaboutcars.com back when Farago was around, and his launch of TrueDelta awhile back.

I'm not arguing flaws or no flaws; you two are far more sophisticated there then me....however, I've submitted data to his service and therefore received free reports for many years now. The insight you can get into car ownership from detailed owner-submitted data is really insightful and fascinating.

He is the real deal.

LVDell

Thanks Joe. We have actually be conversing back and forth offline since the thread started.

mkaresh

To provide an additional benefit, I recently enhanced the related repair history survey so that it can (optionally) be used as a personal car maintenance record for cars 2000 MY and newer.

More participants remain needed to fully cover all model years. Updated results in May.

Not yet signed up? Details here:

Car reliability research

mkaresh

We have updated reliability stats for the Boxster and Cayman that include owner experiences through March 31, 2010. In terms of repair trips per 100 cars per year:

2005: 71

2003: 95, small sample size

2002: 120

2001: 129

2000: 101

1999: 129

All are about average. The result for the 2000 might be a bit lower than it should be, judging from the results for other model years. Note that these cars are driven only about 5k miles per year on average, and we don't currently adjust for this but do post the average odometer reading.

I'd like to report specifically on the IMS failure rate, but we will need more participants to do this. So far, with 180 986s participating for an average of about six months, only two IMS failures have been reported, and none since last August.

A big thank you, once again, to this forum and deveryone who has been helping. We'll have further updates, possibly including additional model years depending on the number of participants, in August and November.

Porsche Boxster reliability comparisons