Hi @essam ibrahim,
For newer Prados, they tend to have lots of "eco" settings that make it more challenging to extract the best performance. As you experienced, using "S" in the desert instead of "D" can help to remove some of these Eco settings. When in S, always make sure the dashboard says "4". If the number changes, the best way to reset is to move the stick to D and then back to S.
Once you enter the desert, make sure you disable traction control and set "S" mode.