CR indicates requiring a minimum of 100 responses in order to publish the data for any model in any model year.
"Our sample sizes tend to track quite closely with market sales. Individual sample sizes vary from year to year and range from a hundred to several thousand for the more popular models."
The survey is only open to subscribers of either the magazine or the website, as are the results.
Their survey is scientifically designed by experts and they consider it to be both valid and reliable in the data and results.
So it's hard to argue with science and the facts--tesla DU problems are really very minor and insignificant, if they even exist at all. If it were otherwise the CR survey and reports would have clearly identified it--since they didn't it's not an issue.
While we agree on the solid science behind CR data, I would like to caution against calling DU problems insignificant, leave along non-existent. Let's try not to exaggerate. The data clearly show that there is small but statistically significant quantity of cars that have experienced drive unit problems (my P85+ included), however the overall rate of these problems is to small to either present financial problem for the Company, or warrant recommending against buying the car - after all Model S is CR overall top pick second year running.