Early Tesla Model S Powertrain Reliability Issues Come into Question in Low Volume Study

The guys at Green Car Reports, responsible for the hype referring to possible reliability issues for early versions of the electric car's powertrain, have estimated that two-thirds of the first series cars might develop an engine failure. We suggest you take this information with a grain of salt because these are estimates based on a very small volume survey.

The analysis was run in October 2015, back when Plug in America had data from 370 Tesla Model S owners. Green Car Reports specifies that it didn't have any specialized reliability evaluation software and called upon a reliability engineer to estimate the "characteristic life" of the Tesla Model S's drivetrain. The result isn't what you might call impressive, because the numbers showed an estimated average life of 50,000 miles for early Tesla models.

As Green Car Reports explains, the term "characteristic life" refers to the age at which particular parts are expected to fail. Using several mathematic formulas and other calculation tools, the engineer approximated a survival rate of 36.8% for the early versions of Tesla Model S's powertrain. In layman’s terms, the engineer estimates that only a third of the first Tesla Model S electric engines will live past 50,000 miles.

Calculations were based on early versions of the Tesla Model S (before the P85 came out) and took 77 failures and 250 suspends into account. On a global scale and considering Tesla's sales volume, the numbers aren't troubling.

Even the engineer responsible for the calculations above specified that the results shown are valid only if the data was correct, had no selection bias and was random. Since we're speaking of user-submitted data from several countries and immeasurable driving conditions, we're placing our bets on Tesla Motors and not on the naysayers ready to throw bricks at the first signs of weakness.

Tesla Motors declined to comment on the analysis presented by Green Car Reports and didn't answer questions regarding the number of cars serviced on warranty for this potential issue.

Instead, Tesla's spokesperson issued this statement: "Close communication with our customers enables Tesla to receive input, proactively address issues, and quickly fix problems. Over-the-air software updates allow Tesla to diagnose and fix most bugs without the need to come in for service. In instances when hardware needs to be fixed, we strive to make it painless.

I would point you to Elon’s previous comments, here and here, as well as what Consumer Reports recently [wrote]:

Despite the problems, our data show that Tesla owner satisfaction is still very high: Ninety-seven percent of owners said they would definitely buy their car again. It appears that Tesla has been responsive to replacing faulty motors, differentials, brakes, and infotainment systems, all with a minimum of fuss to owners.

And Tesla’s attention to customer service has been effective. Almost every survey respondent made note of Tesla’s rapid response and repair time, despite the lack of a traditional dealer service network. For its early adopters, Tesla has made a practice of overdelivering on service problems under the factory warranty."

Tesla's own statement tacitly admits some reliability issues with the first Model S series, but such problems are common in all areas of the industry and the affected parts have already been replaced under warranty. Furthermore, the company mentions solving those issues for later models and improving build quality, so owners shouldn't worry too much about this analysis.