I am participating in the upcoming bar mock trial as the defence barrister and I'm having trouble starting my cross examination of the second witness. The case is basically a man is accused of taking part in a robbery of a building society and he's accused of being the get-away car driver the second witness has been drinking at a Christmas party and is wearing a ski hat which covers their ears, they are claiming they heard a commotion outside the building society and saw 3 people wearing baseball hats run to a car. They suggest the car is a bmw (when it is infact a rover) and they threw a bag into the foot-well of the car. They also suggest that one of the robbers shouts "thats it wheels get this thing moving" and the car drives off fast.
Could anyone help me with how to start my cross examination of this witness please?