In Tremors, after Burt and Heather kill the second graboid, they climb to their roof. Later, Val radios them with a plan to hop in their truck and get some help from Bixby, as they have the last truck in town that can make it.
Conveniently for the plot, a graboid destroys their truck at this moment.
Why did it do that?
This graboid was away when the truck arrived, so it couldn't know this inanimate object was a car. Nobody was in the truck at this time, and the engine seems shut down, so it couldn't be making noises. Every other time a creature attacks a vehicle during the movie, someone was inside / on it.
In Wikia's Burt Gummer's page, it says that :
"[...] the plan is made moot when the creatures start tearing the town apart from the below and eat the tires on their cars."
... But I was under the impression that the graboids were trying to feel the foundations of the buildings on which the characters were standing, and not randomly destroying objects on the ground.
So, is there a in-universe explanation as to why the graboid decide to destroy Burt's and Heather's truck?