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      03-09-2013, 07:05 PM   #82
Artmasterx's Avatar

Drives: 2007 BMW 335i
Join Date: Jun 2008
Location: MA

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2006 Volvo V70R  [5.00]
2007 BMW 335i  [5.00]
Everyone, I have compiled initial statistics based on 183 responses so far.

Everyone help out by voting!

I switched to a binomial-based distribution which is better for proportions (always exists between 0 and 1):

Plot of estimated failure rate during specific mileage intervals:

Plot of estimated failure rate before a specific mileage (perhaps more interesting to some of us):

(I didn't really propagate the uncertainty correctly, so the uncertainty is probably larger at higher mileages)

Looks like there may be a lot of failures between 60-75,000 miles, and a relative lull in failures between 75-100k miles (though still uncertain). This could mean that some pumps fail early and other batches are more robust. However, it could also be a function of the heterogeneous sample of turbo/non-turbo cars, different driving styles, etc...

Still, predicting a 50% chance of failure before 75,000 miles kind of sucks! (and ~65% before 100,000 miles)

Interesting nonetheless!
Current: 2007 335i sedan
Alpine White | Sports | Premium | Cold | Comfort Access

FORMERLY: 128i coupe
Alpine White | Sports Package | Black Leather