You see alot more brake dust on the front wheels because the front brakes do more of the braking than do the rears. On most rear wheel drive vehicles like your Crossfire, about 60% of the braking is engineered to be performed by the front brakes. On most front wheel drive vehicles, about 80% of the braking is engineered to be performed by the front brakes. The front brake pads on the front of just about any vehicle have a larger friction material surface area. More braking in a larger area...more dust. Many people never bother to rotate their tires either. It's recommended by tire manufacturers to be performed every 5,000 to 6,000 miles (even Chrysler recommends that the tires be rotated from side to side in the owner's handbook, though most Crossfire owners probably never go to this expense as many have directional tires that would require dismounting & remounting...a big expense in time, money, & wear to the wheels if performed this often). When rotations are not performed & they don't clean their wheels, then the front wheels end up with lots of hard to remove brake dust stains. Don't let it happen to you & keep those wheels clean.