RAGEuphoria by bravercoolio and jedijosh920 uses NaturalMotion's proprietary Euphoria physics engine and Rockstar Game's proprietary RAGE engine to their best potential for Grand Theft Auto V.
Tons of research and testing was done using a combination of Euphoria files from Red Dead Redemption, Max Payne 3, and Grand Theft Auto IV.
No longer will you see pedestrians instantly plop down on the floor when you shoot at them, RAGEuphoria uses advanced research and configuration to make them balance with grace and style.
Some other notable features are the self-preservation AI aspects such as pedestrians grabbing onto things when falling down to reduce their fall damage.
RAGEuphoria is essentially a specially mixed recipe of the best Euphoria aspects from each of Rockstar's games.
Some tests, examples, and research are shown here: