Tesla pushed back the delivery estimates for its all-electric SUV the Model Xto "the second half of 2016" from "early 2016" Thursday.The automaker had a record month of reservations in August, according to Electrek, receiving 1,730 last month to bring the total to 31,195. The backlog could explain why the website updated its expected delivery date.The automaker is expected to begin limited Model X deliveries September 29, as planned. Tesla initially planned to continue filling existing reservations for the rest of 2015 and then open up sales for those who hadn't preordered in early 2016. Now it looks like people filling out new orders will have to wait for later in 2016. The Model X has been undergoing testing on the road.This is not the first time Tesla has altered its delivery model for the Model X. Tesla first projected deliveries of 55,000Model S and Model X for 2015, which it then softened to between 50,000 and 55,000 in a second quarter investor letter.The updated projectionwas a result of ramping up production for the Model X."We do think it's going to be a challenging production round on the [Model] X," Tesla CEO Elon Musk said on a conference call with analysts after the company reported second-quarter earnings."We only want to deliver great cars. We don't want to drive to a number that's greater than our ability to delivery high-quality vehicles."Tesla CEO Elon Musk also saidthat the Model X "may be the hardest car to build in the world."For now, it looks like hopeful Model X drivers who haven't preordered will have to wait a little longer. In the meantime, learn everything you need to know about Tesla's next car.Join the conversation about this story Click here to read full news..