Originally scheduled for delivery in 2013 before getting pushed into this year, Tesla just announced in its earnings statement that the Model X crossover is getting pushed once again — this time into the third quarter of 2015. The company cites "significantly more validation testing time" as a key reason for the delay.
Work continues on the finalization of Model X with the testing of Alpha prototypes and initial builds of the first Beta prototypes. Model X powertrain development is almost complete with the early introduction of Dual Motor drive on Model S. We recently decided to build in significantly more validation testing time to achieve the best Model X possible. This will also allow for a more rapid production ramp compared to Model S in 2012.
Tesla's language is both apologetic and defensive, calling the delay "a legitimate criticism" of the company because it'd rather "forgo revenue [...] than bring a product to market that does not delight customers."
As an all-wheel driver vehicle, the Model X relies in part on the dual-motor drivetrain developed for the recently introduced Model S P85D, so that's at least signed off — it's just the rest of the car that apparently still needs some work.