Cars should look the same, in fact id be ok if there were only a handful to choose from, like a small passenger car, a larger van, and then a truck and that's it.
Do you pick your hammer and wrench based off what color it is or how well it performs for the cost?
When things become price optimized, there really is little left to differ on because of the physics of cars, much like the physics of hammers and wrenches.
