I did research and found that the average for assembling a car was nearer 35 hours: this is from 2008:
Motor Trend:
When Harbour adds up all the man-hours it takes to build a car or truck, including stamping, assembly, engine and transmission manufacture,
Hyundai was seventh of seven majors, at 35.1 hours per vehicle in North America.
Ford Motor Company was sixth, at 33.88 hours, a 3.7-percent improvement over last year,
Nissan was fifth, at an estimated 32.96 hours, or 8.8 percent more time than the previous year, and GM was fourth, at 32.29 hours, a 0.2-percent improvement.
Honda was third, at 31.33 hours, a 2.3-percent improvement.
This is ten years ago but I would think 40 hours was reasonable for Tesla currently - with an expectation that it can be lowered to 30 hours a vehicle..on the Model 3 at 5-6000 a week.