NNNOOOOOO!!!!!! Another horrible leather thread? ANOTHER???
Seems like these pop up at least once a month with bad advice, bad techniques, and lack for clear information being spread.
DO NOT use something abrasive on your leather. The urethane coating shouldn't be treated in this matter. The best thing you can do for leather is to simply keep it clean. Monthly wipe downs of something like Leatheriqe Prestine Clean, Leather Master Soft Cleaner, or even 20:1 diluted Woolite should help a lot. Ditch all the garbage "conditioner" products you normally find which actually increase wear on your seat. Your leather is coated and doesn't need "conditioning."
If anything, do a little research and read one of the other dozen threads on proper leather care, and DO NOT use a magic eraser on your seats!