Car Gravity issue (A-Chassis)

Hey guys, so i work on a Big project sind over 2years and did not let me stop yet, i solved all issues i had, now i need some help or tips how to fix this Gravity bug, so i use the Roblox Reallife Gravity (35) and actually most things work good but one thing i still did not fix yet is that Cars feel like weightless.
My Cars using newest A-Chassis and because of some test there Weight Is 10000Pounds… so more than they actually should have but they still feel so weightless with the RL Gravity…

Example Video:

Credits to my friend Falko who recorded it.