Any resource like...

[DeletedAccount1111]

... making cars easier to roll when crashing with another? Also something that kills people when running over them

[xXMADEXx]

To make the cars kill someone when it hits them, use:

  
    -- Event: onPlayerDamage/onClientPlayerDamage 
    isElement ( ) -- check to see if there was an attacker 
    getElementType ( ) -- check to see if the element was a vehicle 
    killPed ( ) 
  

To make the cars roll easier, you'll need to make a custom handling for the vehicle.