The S2 chassis is basically the same as the S1 chassis, except that the side rails have cut-outs to improve access to the car. These cut-outs have interlocking re-inforcements bonded in polace during assembly to minimise the impact of this change. The torsional regidity of the car is actually improved by about 7%, at the expense of a small reduction in bending strength. The first bending and torsional natural frequencies have also dropped by a few percent to about 70Hz. The chassis weighs about 4kg more than that of the S1.
The VX220 chassis is similar but is wider, heavier and longer to accomodate the GM engine.