The Tesla Model X has been delayed again, likely until the second quarter of next year.

In a letter to shareholders released on Wednesday, the Palo Alto, Calif.-headquartered company cited "extensive development work" but said Model X production should start in spring 2015, Edmunds.com reported.

"Model X efforts are on track to ramp up production in the spring of 2015," Tesla said in the letter, as quoted by Edmunds. "We have just completed the final studio release of the vehicle."

Tesla expects to deliver the new vehicles in summer 2015. Electric car enthusiasts will need to put down a $5,000 deposit to reserve a base Model X, but the carmaker hasn't yet announced full pricing.

 "Extensive development work on Model X is underway and we expect to have production design prototypes ready in Q4," Tesla said in the letter. "The tooling process has started with several suppliers and we expect production design prototypes to be ready in Q4 of this year."

The company showed off a Model X crossover prototype in February 2012 and originally announced that the car would launch in 2013 before it was pushed back another year.

In a recent interview, Tesla CEO Elon Musk cited his "perfectionist" nature and said the car wasn't quite ready.  

"It's damn hard to make an SUV in particular that is beautiful and yet incredibly functional at the same time," Musk told Bloomberg. "It's a harder design problem than the Model S."

The new Model X is expected to have a roomy interior and optional all-wheel drive.

Tesla has also been busy expanding business into Asia and Europe as well as increasing factory capacity to build more Model S vehicles and launch Model X production. 

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