At the end of June, Tesla pushed hard to finish 5,000 Model 3s a week. It may have pushed too hard.

New internal documents acquired and reported by Business Insider show that of the 5,031 cars produced in the last week of June, 4,300 had some problem that required rework.

In auto industry terminology, the percentage of cars that pass company inspections as they come of the assembly line is called the "first pass yield."

Industry experts noted than the industry average first-pass yield ranges from 65 to 80 percent. In the last week of June, Tesla's was 14 percent.

Tesla factory screencap from SF Bay Area CBS video

Tesla factory screencap from SF Bay Area CBS video

The documents show that each car took an average of 37 minutes to repair after it left the factory.

In response to the report, a Tesla spokeswoman said in a statement to Green Car Reports, "Our goal is to produce a perfect car for every customer. In order to ensure the highest quality, we review every vehicle for even the smallest refinement before it leaves the factory. Dedicated inspection teams track every car throughout every shop in the assembly line and every vehicle is then subjected to an additional quality control process towards the end of line. And all of this happens before a vehicle leaves the factory and is delivered to a customer.... We've also seen huge improvements on Model 3 quality."

The statement also notes that factory efficiency has improved while the labor hours to produce each car—affected by the rework—have declined by 30 percent.

Tesla also notes that many of the issues are minor, perhaps like the mismatched door panel on one Twitter user's new Model 3.

(Tesla has reportedly reached out to this customer to correct the mistake.)

By the first week of June, Tesla's General Assembly Line 4—running in a tent adjacent to the main factory—had begun producing a small number of Model 3s, and the main Model 3 assembly line (GA3), had been reconfigured to put less emphasis on automation. There were still teething problems with both lines as recently as early August.

Even if the first pass yield has improved by the same 30 percent as labor efficiency, the number of cars needing rework, at a run rate of 5,000 Model 3s a week, would represent a lot of cars. If Tesla is committed to delivering perfect cars to customers, that could account for all the Teslas stacking up in parking lots near the factory and around the San Francisco bay area.