There's only so much you can do with numbers. Not too long ago, Plug In America set up a survey page to get information from Model S owners about their cars (it's still available here). Only a few hundred people filled in the form, which asked for details on the car's longest-ever trip, odometer and current battery capacity, and - most important for this post - any powertrain component failures. Those early Model S vehicles were the result of a young car company trying to build a vehicle that simply hadn't existed before, so some challenges were to be expected, but the depth of the problem might be bigger than we knew before.
Based on the information voluntarily provided by 327 early Model S owners, Green Car Reports has calculated that over 60 percent of all 2012 and 2013 Model S EVs "can expect a drivetrain failure within 60,000 miles." That may seem like a shocking headline but the sample size is pretty tiny (about 25,000 Model S vehicles were sold in that time frame), so there are grains of salt that need to be taken here. It also matters how the survey (or respondents) defined "powertrain component failure", but the GCR article makes it seem like a replacement motor is the most common issue.
It's worth pointing out that, depending on when these replacements happened, they may be covered by Tesla's Model S warranty – so the issue isn't as bad for the drivers as it might be for the company. The original warranty covered things other than the battery for, "the repair or replacement necessary to correct defects in the materials or workmanship of any parts manufactured or supplied by Tesla that occur under normal use for a period of 4 years or 50,000 miles (80,000 km), whichever comes first." It was updated to an 8-year, unlimited mile warranty for these affected cars in 2013. The battery is covered for at least 100,000 miles.
Whatever the numbers show, there are serious questions about the reliability of early Model S vehicles. In fact, after raving about the car when they first got it, the editors over at Consumer Reports took the Model S' "average" reliability rating and instead bestowing it with a "worse-than-average" rating. This, too, was based on owner surveys, but in this case there were 1,400 of them.
Nonetheless, there is a bigger issue at stake here, and that is Tesla's inability so far to respond to GCR's entirely reasonable list of questions about the Model S and its reliability. Things like, "How many motors has Tesla repaired or replaced in 2012 and 2013 Model S cars to date?" and "What does the company's own reliability data indicate about the percentage of cars that will require motor replacements over the life of the vehicles?" We gave Tesla another chance to respond to those questions, and heard back that more information will be coming soon. Stay tuned.