"In order to modify automotive software for the purpose of 'diagnosis and repair, or aftermarket personalization, modification, or other improvement,' the modifier must use a substantial amount of the copyrighted software - copying the software is at issue after all, not wholly replacing it," the AGA claimed. "Because the 'heart,' if not the entirety, of the copyrighted work will remain in the modified copy, the amount and substantiality of the portion copied strongly indicates that the proposed uses are not fair."