The men from the Esso station are initially antagonistic towards Rosaleen, and their actions are connected to the events leading up to her arrest:
* They refuse to serve Rosaleen after she attempts to buy a drink. This is likely due to the racist attitudes prevalent in the South during the 1960s.
* They call the police on Rosaleen after she spills her drink on one of them. This is a direct consequence of their prejudiced behavior.
However, they do not follow the police car or engage in any further actions after Rosaleen's arrest. Their interaction with Rosaleen is a brief, but significant, event that sets the stage for the novel's central themes of racism and prejudice.
It's possible you're thinking of a different part of the book or another story entirely.