I would think that the most gentle way to dry a car is to let it air dry. That's gotta be less scratch prone that a towel of any kind or a silicone blade. You can always use a towel (micro friber even if that's what you like) to dry the less exposed areas in doors and under hoods . . . though I'm not sure I understand why you wouldn't want to just let them air dry as well.

If this product really works, I'd just let it air dry. That one's a no brainer.