What are the similarities between the Elise S1 and the S2 aside from the obvious looks? Suspension / chassis the same?
It seems the elises.co.uk site has answered most of questions
Lotus Elise S2 Chassis
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.