Coming from a racing background, there are several design ideas that I would like to suggest.
Enough room to fit a tire width at least 4 sizes wider than stock at the front and 6 sizes wider in the rear.
The ability to lower the car a few inches using aftermarket or upgraded suspension, without compromising handling (like bump steer or bottoming out suspension bits on the frame).
A suspension package with higher spring rates, adjustable damping, and a stiffer sway bar.
Torque vectoring that will help keep the vehicle stabile while going around corners fast.
An interior package that includes a better bolstered seat and race inspired steering wheel.
Bolt on aero modifications like front canards and maybe a rear diffuser, that can be removed easily for daily driving.
Driver adjustable front rear biased motor output.
An on screen track map that shows lap times and sectional course times, with colors overlaying the track showing if times have increased or decreased.
I would keep going but I think I will save some ideas for later pondering.