It expresses a brutal force usually of social nature (a truck carries the goods intended for general use); it has a double meaning: it annihilates obstacles, but also kills the passer-by…
drive: a success
sit in it: soon you will find happiness
a track pulling into you: the risk of being crushed by the colossal force, such as a political group, the news creating public opinion, police or judicial apparatus
if the coming truck is shrinking, instead of enlarging: a sign that the dreamer overestimate his/her opponent, and will come eye to eye with him/her.