The superlight cars were deliberately a basic but known specification and definitely supported the "Add Lightness" mantra. However, depending on the original owner, the spec could be modified from new so we see Superlight cars coming out with wipers, heaters, windscreens, spare wheels (or at least their carriers) and, heaven forbid, paint. Some cars came out with GRP panels to save money over their more costly carbon fibre equivalents. The R500 chassis did have a weight saving with the strengthening bracket for the spare wheel deleted and I expect the aeroscreen only variants (there were two) have the bracket for the wiper motor excluded plus the wiper washer/buttons deleted from the dash layout for obvious reasons. On the whole though as Anthony says, the desirable items are add ons. I was going to say cosmetic but that wouldn't be correct for the LSD and dry sump systems