Generally, people will widebody a street car for the aesthetic. They are imitating the production race cars that use wider tires to increase traction; wide enough tires don't fit under the stock bodywork, so the fenders come out further to cover the wider tires for aerodynamic purposes.

The Lamborghini Huracan GT3(production car pulled off the line to be made into a race car) is about 80 inches wide, compared to ~76" for the stock Huracan. For comparison, a Prius comes in at a nice ~69" and the F150 is currently ~80".