In order to carry the extra weight of batteries in the New Beetle, it will require stiffer springs.
The rear of the vehicle is design to carry 150-200kg (330-440lbs).
There will be approx 16 batteries in the rear, each weighing 19.3kg (42lbs).
This is a total weight in the rear of 310kg (680lbs).
Therefore new springs will be needed which can handle an additional load of 110-160kg (240-350lbs).
These springs were custom made by Coil Spring Specialists in Kansas for approx $170.
Comparison of new spring (top) to stock spring (bottom). The new spring has more coils and is of thicker material.