How can I achieve realistic character movements on vehicles?

wmv:robloxapp-20210816-2114475.wmv (1.3 MB)

mp4:

As you can see, the character moves very smoothly and realistically.
I thought that to achieve this kind of movement, the developer of this game used a rag doll and left the rest to Roblox physics.
So I tried it myself:

wmv:robloxapp-20210816-2114130.wmv (1.5 MB)

mp4:

Are there any tips and tricks to achieve more realistic movements like in the first video?