Audi A4 2001 Owner's Manual page 9

Side impact design features
In the floor area, the cell consists of three
large tailored blanks, which ensure a stable
connection between the front and rear of the
vehicle.
Weight-saving optimisation of deformation
characteristics in the event of a side impact
was achieved by the use of an aluminium
extruded profile in the sill.
"tailored blanks" are made-to-measure
sheet metal parts with varying material
thickness.
SSP254_055
SSP254_056
9