Tesla reached its milestone of building 5000 Model 3 vehicles in the final week of the quarter and in the process became "a real car company", chief executive Elon Musk said.

"We did it!!" Musk proclaimed in an email to employees obtained by Bloomberg News on Sunday. "We either found a way or, by will and inventiveness, created entirely new solutions that were thought impossible."

Hitting the target is another against-all-odds achievement for Musk, who first revealed the Model 3 in late 2016, and a relief for customers who have waited patiently for their electric cars. The 47-year-old Musk said he celebrated his birthday earlier this week at the factory, where he had been posting photographs of drive units and the paint shop to his social media accounts. To make the goal, he even built a tent to house a third general assembly line at the Fremont, California, factory.