Tesla Model 3. Timothy Artman/Tesla Tesla produced just 260 of its Model 3 sedans in the third quarter, widely missing its target for the much-anticipated new car, because of production bottlenecks.

Tesla CEO Elon Musk said in August that the company planned to produce 1,500 Model 3 cars in September alone and ramp up to 20,000 cars per month in December.

"Model 3 production was less than anticipated due to production bottlenecks," Tesla wrote in its investor letter Monday. "Although the vast majority of manufacturing subsystems at both our California car plant and our Nevada Gigafactory are able to operate at a high rate, a handful have taken longer to activate than expected."

Tesla added that there are "no fundamental issues with the Model 3 production or supply chain" and is aware of what needs to be fixed.

It's a big miss for the most highly-anticipated car of the year, but doesn't come as a complete shock. Musk had said that the first six months of Model 3 production would be "hell." Tesla also missed its targets when it first started producing the Model S and Model X.

The Model 3 is Tesla's first mass-market vehicle starting at $35,000. Tesla secured 455,000 orders for the vehicle as of August. Those who order a Model 3 today will have to wait until at least mid-2018 for delivery of the vehicle.

Tesla said it produced 25,336 vehicles total in the third-quarter, with 260 being Model 3 sedans.

The electric car maker delivered 26,150 vehicles in the third quarter — 14,065 Model S sedans, 11,865 Model X SUVs, and 220 Model 3 sedans. Tesla said it was its best delivery quarter in company history, representing a 4.5% increase over the third-quarter of 2016.