Tesla Motors' (TSLA) - Get Report Elon Musk violated one of the classic truisms of business: "under-promise and over-deliver."

Now, Musk's bad summer has gotten even worse as his electric car company disclosed in a holiday weekend release that its vehicle deliveries in the second quarter fell well short of the company's own expectations.

Tesla announced Sunday that it produced 18,345 vehicles in the second quarter of 2016 -- just under 2,000 per week -- a 20% increase from the previous quarter.

However, the seemingly strong production numbers came at a high cost. "Due to the steep production ramp, almost half of the quarter's production occurred in the final four weeks," the company said in its statement. As a result, Tesla's deliveries in the quarter disappointed at 14,370 vehicles, below the 17,000 the company expected.

About two-thirds of the deliveries in the quarter were of the Tesla Model S, and the remainder were of the newer Model X.

5,150 cars that were ordered in the second quarter will be delivered in the third quarter, "more than a third of the number of cars that completed delivery in Q2," according to the company, and about double the vehicles in transit to customers at the end of the first quarter.

During the second half of the year, Tesla said it expects to deliver 50,000 cars, about as many as it produced and delivered in all of 2015. The company forecast a production rate of 2,200 per week in the third quarter and 2,400 per week in the fourth quarter.

In May, despite a management exodus, Tesla announced a massive production ramp up. Musk said that Tesla would produce a total of 500,000 cars by 2018, while he had previously said the company would hit that target by 2020.

Musk stressed manufacturing after reporting Tesla's first-quarter results.

"We take manufacturing very seriously at Tesla. It's the thing that we need to obviously solve if we're going to scale and scale rapidly and make the cars more affordable," he said on the May 5 analyst call. "That is going to be the primary focus of Tesla, is how do we get super-good at making large, complex objects?"

A few weeks later, the company announced plans to raise $2 billion in an offering underwritten by Goldman Sachs (GS) - Get Report .

The numbers release -- on the Sunday of a major holiday weekend -- is the latest in a string of bad news for Tesla.

On June 21, Tesla offered to acquire another Musk endeavor, SolarCity (SCTY) , a move largely condemned by Wall Street analysts as bad for Tesla. On July 1, Credit Suisse analyst Patrick Jobin wrote that, additionally, the proposed acquisition would harm SolarCity shareholders as the $2.8 billion offer "grossly undervalues" the company.

On June 30, the National Highway Traffic Safety Administration announced that it was investigating a May 7 collision that killed a Model S driver who was operating his car in autopilot mode.

In a blog post, Tesla blamed the crash on "the extremely rare circumstances of the impact" and that the autopilot feature is still in beta.

"This is the first known fatality in just over 130 million miles where Autopilot was activated," the post read. "Among all vehicles in the US, there is a fatality every 94 million miles. Worldwide, there is a fatality approximately every 60 million miles."

In April, Tesla recalled about 2,700 Model X vehicles after discovering a potential safety hazard.

Tesla shares were down 0.23% in after-hours trading Sunday evening and have dropped about 12% in the past three months.