▁at ▁times ▁the ▁regular ▁Formula ▁ 4 0 0 0 ▁field ▁was ▁complement ed ▁by ▁vehicles ▁compet ing ▁in ▁the ▁new ▁O z ▁BO SS ▁category ▁for ▁open ▁wheel ▁racing ▁cars . ▁In ▁ 2 0 0 7 ▁numbers ▁had ▁dropped ▁to ▁the ▁point ▁they ▁could ▁no ▁longer ▁form ▁races ▁by ▁themselves ▁and ▁were ▁am alg am ated ▁into ▁the ▁O z BO SS ▁category . ▁As ▁part ▁of ▁this ▁am alg am ation , ▁the ▁cars ▁themselves ▁were ▁re - bad ged ▁again ▁as ▁Formula ▁ 3 0 0 0 V 6 . ▁ ▁The ▁drivers ▁in ▁the ▁series ▁in ▁the ▁ 2 0 0 0 s ▁were ▁a ▁mix ▁of ▁older ▁drivers ▁who ▁owned ▁their ▁own ▁cars , ▁or ▁very ▁young ▁Ocean ic ▁or ▁South ▁Asian ▁drivers ▁looking ▁to ▁make ▁a ▁name ▁for ▁themselves ▁on ▁the ▁international ▁scene . ▁Although ▁techn ically ▁using ▁cars ▁just ▁a ▁step ▁below ▁Formula ▁One , ▁the ▁lack ▁of ▁competition ▁in ▁the ▁series ▁means ▁that ▁drivers ▁t ended ▁to ▁progress ▁from ▁Formula ▁ 4 0 0 0 ▁to ▁a ▁minor ▁series ▁in ▁Europe ▁( Will ▁Power ▁- ▁British ▁Formula ▁ 3 ) ▁or ▁North ▁America ▁( Sc ott ▁D ixon ▁- ▁Ind y ▁L ights ). ▁Alternatively ▁drivers ▁moved ▁to ▁any ▁of ▁the ▁Australian ▁sedan ▁based ▁champion ships ▁such ▁as ▁Super c ars ▁or ▁Australian ▁GT . ▁ ▁From ▁ 1 ▁January ▁ 2 0 1 2 , ▁Formula ▁Hold en ▁cars ▁with ▁a ▁competition ▁history ▁established ▁prior ▁to ▁ 3 1 ▁December ▁ 1 9