Vehicles do not gain benefits from cover in the same way as infantry. However, vehicles can move into protected positions and use terrain to mask their more vulnerable parts in the following way. Any vehicle that is in or behind cover (e.g., behind a wall, just beyond the crest of a hill or a wrecked vehicle, in woods or jungle, or something similarly substantial) is considered to be 'hull down'. A hull down vehicle is trying to keep itself out of the line of fire as much as possible, so it counts all penetrating hits as glancing hits instead, as shown in the diagram on the next page.
Diagram: "Hull Down" — a Predator tank positioned hull down behind a ruined wall, with an Eldar skimmer beyond it. Caption: "Predator – hull down. Glancing hits only."
Smoke Launchers: Some vehicles have small launchers mounted onto them that carry smoke charges (or a more sophisticated equivalent in the case of skimmers). These are fired to temporarily hide the vehicle behind concealing clouds of smoke and are most often used when it is moving in the open. Once per game, after completing its movement, a vehicle with smoke launchers can trigger them (it doesn't matter how far it moved). Place some cotton wool around the vehicle to show it is concealed by smoke.
The vehicle may not fire in the same turn as it used its smoke launchers, but any penetrating hits scored by the enemy in their next Shooting phase count as glancing hits. After the enemy's turn, the smoke disperses with no further effect.