Why Tesla Model X is late (hint, it could be the falcon doors)

Watching Tesla Motors first show off its Model X SUV at a blingy event three years ago, this reporter heard a lot of "oohs" and "ahhs" when the car's falcon-winged rear doors reached for the sky. Now, those doors are likely causing the automaker's engineers to emit a lot of "args" and, likely, a bunch of unprintables. Such is the price of progress.

Initially slated to start production in late 2013, Tesla has pushed back production of the Model X to sometime this year. Company CEO Elon Musk has already said that the doors are a challenge, but Green Car Reports talked with some unnamed suppliers to learn more about how, exactly, those doors are creating delays. It turns out, those heavy doors require large torsion springs that need to be perfected. Additionally, making sure the door seals are sufficient, as well as ensuring that those doors can withstand enough abuse to give the Model X a top safety rating are also keeping the SUV from going into production.

Last November, Musk, responding to a question from Goldman Sachs' Patrick Archambault, confirmed that the Model X would have a third-quarter 2015 launch, and that the doors were causing much of the delay. Additional issues have popped up with the production of the model's second row of seats and the company's efforts to replace the Model X's side mirrors with video cameras – which would improve aerodynamics (always key for an electric vehicle's single-charge range) – are being stymied by rules that say mirrors are still required for safety.