“We tried to make the car as similar to the [Model 3] as possible except in the case where a change was necessary to achieve SUV functionality…[all] while still having a low drag coefficient and not increasing the frontal area too much,” he detailed. Overall, Musk concluded that CdA (automobile drag coefficient) and mass of the Model Y only affect 8-10% of the battery range when compared to the Model 3.
The design of Tesla’s Model Y and lessons learned from Model 3 production also led to some manufacturing improvements for the electric crossover. Musk detailed how the Model Y underbody was switched to aluminum casting instead of stamped steel and aluminum pieces, which greatly simplifies the moving parts involved in making the vehicle.
This change effectively means that initially, using two castings to make the structure will take the process from 70 parts to 4 (castings plus joiners), and once the “big” casting machine comes into operation, the process will have brought the process from 70 parts to 1 (casting only). Using casting over stamping reduces the weight of the Model Y, improves MHB (heat produced), lowers cost due to the smaller number of parts necessary, and significantly drops capital expenditure on robots.