The problem with washing cars in the past is that the dirt and abrasive debris would stay mixed with the water. When this happens, all you're doing is re-introducing all of that abrasive material back onto the paint...thus causing swirls!
The only way to properly wash your car is to use the 2-bucket method...2 buckets, each with a Grit Guard placed at the bottom of the bucket. One bucket is for your wash/soap solution, and the other bucket is for carefully rinsing out your wash mitt. After washing a panel, place your wash mitt in the rinse bucket, and gently agitate it against the Grit Guard. All of the abrasive dirt should safely fall to the bottom of the bucket where the Grit Guard's patented design helps keep it trapped down there away from your wash mitt. Then take your wash mitt and follow the same procedure in your wash bucket. Now you have a clean wash mitt that is ready to be applied again to a small section of your dirty car. If done properly, your wash bucket should be (almost) as clean at the end of the job as it was in the beginning.
TIP: Buy a Grit Guard in each color...then if your two buckets are the same color, you'll know which bucket is which based on the color of the Grit Guard (Red Grit Guard for Rinsing, and Black Grit Guard for washing...as an example).