Well, sometimes the 1-1-1 goes transparent... Or 1-0-0 or any variant... By the way, to be sure that my car won't have any "holes", I use 8-8-8 to the darkest black shades in car shape (engine cover air intake and else... For adverts, I use 16-16-16 and for liveries, I use 32-32-32...
If you want to be more precise, check the original car JAMs to see which color tones are used on blacks...
GPGSL-3: Fox race driver and team manager - 2011-2012 Constructor Champion - 2012 Driver Champion
Season 9 - #18 Erick Von Draxeler - #35 Marcus Bongardt