Slight crease to the underside of the outer box.  In doing some research, while x5531 shows up as Elite series on the Mattel site, the red box is different than the black box 'elite' models as the red box model only has front opening doors and no antennas.  The URL on the box says hotwheels-elite.

My guess is the red box hot wheels were produced as a heritage models at a slightly lower price points but then got rolled back into the elite series.  I've seen some versions of other cars called elite heritage which is what I suspect this is.

Shipping is free within the conus.