the 6 cylinder sound runs from patch 1.30 on the following vehicles: All SCS standard trucks!
Scania RS R4 T and T4 by RJL
MAN TGX By Madster
MAN TGX2010 by XBS
50 Keda DAF XF
Volvo fh2012 ohaha
Volvo FH 13 + 16 Classic by Ohaha
Credits: adi2003de, kriechbaum and many more