I am sure someone else will have a more detailed textbook answer, but from my experiences a short wheel base car is good for tight tracks where having a car that transitions quickly and steers sharply is beneficial. A long wheel base makes the car less "athletic" feeling. More stable but transitions slower and has a larger turning radius. Better for long flowing tracks with large sweepers. That is where I use wheel base changes. To me it's finding the right balance of being able to carve the infield, and carry enough corner speed on the sweeper.