[MTrenk]

Narrowing track width of an existing car would certainly render the suspension geometry created by the manufacturer useless. However, active suspension is not necessary when considering doing your own, new suspension geometry. Suspension geometry is designed around your tire of choice, aerodynamics, and chosen dimensions of the car. (Seems backwards, considering we change to different tires on our road cars all the time... doesn't mean it's the best solution.)

Check out the Nissan Delta Car

Although rather unconventional considering the common racecar methodology, it works well, and is also quite competitive!