here is some advice,it will happen so fast your head will be spinning, by the time you have worked out whats going on it will be over. you will be trussed up like a xmas turkey,thinking wtf went on there.
how do i know ? one of our drivers running out of manor park runcorn for business post in a scanny topline pulling a decker got hijacked going to brum on a trunk in 2005. ex squaddie infantry he was switched on, ex iraq,blah blah blah,said they took it of him like takin sweets of a kid,got the truck back found in knowsley empty,got the driver back after he had been takin on a joyride.
if it happens to you just give them what they want.
you wont have time to be a hero and you will get no thanks of anyone for being a hero.

some videos and info here
http://www.trainforlife.co.uk about being aware and what hi-jackers do