The ordering guide you can see here also exposes three different sets of wheels with or without run - flat tires, a large handful of metallic exterior paint options, various leather options, and M Sport Package, and a Luxury Package, among other things. (topspeed.com)
When you consider the two power sources driving different sets of wheels and the two intervening gearboxes, BMW did a masterful job of making the i8 an exceptional driver. (cnet.com)
Compared to the A6, the S6 takes on front and rear fascias that are slightly more aggressive, but outside of a different set of wheels, that's really all that sets the S6 apart from the A6. (topspeed.com)