Acronym for " Groupe de travail en matière de Roulement et de Freinage" (i.e., Working Party on Brakes and Running Gear) on http://www.unece.org/trans/main/wp29/wp29wgs.html
GRRF
Meaning of GRRF in English
English dictionary of automotive terms. Английский словарь автомобильных терминов. 2012