▁they ▁would ▁be ▁during ▁a ▁regular ▁race ▁ca ution , ▁and ▁a ▁second ▁green - white - check er ▁attempt ▁would ▁be ▁made , ▁up ▁to ▁a ▁maximum ▁of ▁three ▁attempts . ▁From ▁ 2 0 1 6 ▁until ▁August ▁ 2 0 1 7 , ▁the ▁rule ▁was ▁changed ▁so ▁that ▁an ▁" over time ▁line " ▁was ▁established ▁( us ually ▁half way ▁on ▁the ▁pen ult imate ▁lap ), ▁and ▁if ▁a ▁ca ution ▁on ▁a ▁green - white - check ered ▁attempt ▁occurs ▁before ▁that ▁line ▁is ▁passed , ▁another ▁attempt ▁is ▁made ▁at ▁a ▁restart , ▁until ▁a ▁valid ▁restart ▁has ▁been ▁made ▁( defined ▁as ▁the ▁race ▁leader ▁reaching ▁the ▁over time ▁line ▁under ▁green ). ▁Begin ning ▁at ▁Wat kins ▁Glen ▁in ▁August ▁ 2 0 1 7 , ▁NAS C AR , ▁seeking ▁to ▁eliminate ▁controvers ial ▁finish es , ▁moved ▁the ▁over time ▁line ▁back ▁to ▁the ▁start - fin ish ▁line , ▁essentially ▁returning ▁to ▁the ▁ 2 0 1 0 - 2 0 1 5 ▁rules ▁but ▁with ▁un limited ▁attempts ▁to ▁finish ▁under ▁green . ▁ ▁Ca ution ▁on ▁a ▁valid ▁green - white - check ered ▁restart ▁ ▁The ▁race ▁will ▁have ▁no ▁further ▁extensions ▁once ▁the ▁leader ▁has ▁reached ▁the ▁" over time ▁line " ▁under ▁green ▁on ▁the ▁pen ult imate ▁lap ▁in ▁a ▁green - white ▁check ered ▁finish , ▁even ▁if ▁the ▁leader ▁has ▁not ▁taken ▁the ▁white ▁flag . ▁The ▁same ▁conditions ▁apply ▁as ▁though