Gamemode Higher Gas prices

[Haarek]

Police obviously fill their tanks at the discretion of the government. So you wouldn't have to worry about that.

It could also benefit immersion by affecting peoples decision to what cars they choose to drive.
If each car has different fuel efficiency - you could imagine it would play a role in their decision to purchase certain vehicles.

Of course, there's a fine line between just annoyance and realism.