Impact absorbtion...
after the front end of the bonnet, the weel moves back, absorbs, then the open portion of the sill extention folds up agains the sill. Did the vacum tank also help absorb ? sill and firewall appear straight but the shell had to be straightened on a frame machine as the firewall was pushed back over an inch...
The basic design of the E-type originated from racing, the tub had to hold up while the front frame can be just unbolted and discarded.