Elsewhere you’ll find the Audi Q5 with the V6 engine on a “used cars to avoid” list. In contrast, TrueDelta reports good reliability scores for the Q5. Which source is incorrect? Neither of them, really. But the other source is out of date.

The problem with the V6 engine in the Q5 and other Audis: it had a plastic water pump that was prone to leaking. Stress the “had”: most of the failures occurred over a year ago, and those that didn’t fail have since been recalled and replaced. So this specific problem won’t be happening again.

These failures are no longer reflected in TrueDelta’s stats because they occurred back in 2010, and our current reliability stats cover the year that ended on December 31, 2011. The Q5 hasn’t required many repairs aside from the water pump. The other source also covers a year, but in their case the year ended when their most recent survey was conducted, back in April 2011. Go back three quarters in our results, to those released in May 2010 (sorry, this page hasn’t yet been fully converted to the new design), and you’ll find similarly poor reliability scores for the 2009 and 2010 Q5.

The difference: we’ve updated our stats three times since last April. The other source won’t update theirs until October. When a model’s reliability significantly improves (or worsens) you’ll find this reflected in our scores much sooner.

To a certain extent, the Audi Q5’s improvement was predictable. If a poor score is the result of a single very common problem, and the new part is different than the old part, then there’s a good chance that the car model’s repair frequency will improve once this common problem is behind it. We try to note cases like this in the comments. For the Q5 we had, “Very common problem with failing water pumps. Original is plastic, replacement is metal.”