This is the first time I’ve noticed any FH5 car pack discounted on Steam.
(Current discount ends Dec. 4, 2024.)
Steam also currently has all FH5 editions & both expansions (Hot Wheels & Rally Adventure) discounted at 50% off:
…and 80% off all FH4 editions:
…and 50% off all Forza Motorsport editions:
All editions are also currently discounted on the Xbox store too: FH4 (-80%), FH5 & expansions (-50%, but not car packs), & FM (-50%).