May be you have to book a cab for the entire duration of the exam. Might sound sily but that's the only way out. Any metal instruments or keys are allowed to the exam venue which means you cannot take your keys with you and you unfortunately leave the keys unattended. So the only way is to book a rental cab. That way you needn't be worried about driving or leaving the car keys. You needn't have to be worried about driving in the traffic either.

Dear Aspirant,

I suggest you should take a bag with you, to keep all your belongings in it.

Most of the time you are allowed to keep the bag somewhere in the center, like outside the labs, etc. Things usually remain there. Do not worry about it but focus on your preparation.

All the best.