How can one maintain calm nerves and a relaxed state during a driving test, despite having full proficiency in driving?

We advise you to seek Allah's help and ask Him for guidance and success, and to supplicate with the reported supplications such as: "O Living, O Sustainer, by Your mercy I seek assistance; set right all my affairs, and do not entrust me to myself for the blink of an eye," and "O Allah, there is no ease except that which You make easy, and You make the difficult easy if You wish," and "O Allah, guide me and make me steadfast."