Infantry can pose a grave risk to vehicles if they get close enough. With the right weapons, troopers can wreck a vehicle by shooting through vision slits, planting explosive charges on fuel tanks, tearing open hatches to attack crew members or committing some other equally imaginative act of mayhem.
Whilst vehicles can be assaulted by infantry, they cannot be engaged in close combat by them, so when the vehicle's player turn comes around it can simply drive off unless damage prevents it. Alternatively, it could just stand still and fire at the enemy all around it, although this might be dangerous with ordnance or blast weapons!
As mentioned above, vehicles don't take part in close fighting in the same way as units of troops. However, a squad of troops can assault a vehicle and attempt to destroy it. This works as follows:
Launching an Assault
A squad can assault a vehicle by moving 6" towards it, getting into contact in the same way as when assaulting enemy squads. Individual models must move into contact with the closest aspect moving by the shortest route. This means that troops are not allowed to go round the sides or rear of the vehicle unless they start their assault at the sides or the rear.
Hits
Troops attack with the normal number of Attacks: +1 if double armed or +1 because they are assaulting that turn. All attacks automatically hit a stationary vehicle. Vehicles moving 6" or less in their previous turn are hit on a 4+. Vehicles which moved faster than this are only hit on a 6. WS counts for nothing in this case! Skimmers can only ever be hit on a 6 regardless of whether they moved or not, unless they are immobilised, in which case they are hit depending on the distance moved in their previous turn.
Damage
Penetration is worked out as normal (D6 + the Strength of the attacker). Note that this means few troops can actually harm vehicles, as even the lightest vehicle has an Armour value of 10.
Results
No results are counted for close combat against vehicles. The vehicle simply moves away as it wishes in its next turn, while the troops who mounted the assault are free to move, shoot, etc, normally. Thus, assaults against vehicles are very easy to work out – just make your attacks and work out any damage.
Monstrous Creatures
Monstrous creatures are so big and powerful that they roll an extra D6 to penetrate vehicle armour, so their Armour Penetration value is equal to 2D6 + the Strength of the creature.
Melta Bombs
Specialist tank hunting troops are often equipped with melta bombs – fusion based thermic charges which can reduce a battle tank to a burnt-out wreck in milliseconds. Troops armed with melta bombs can treat any of the hits they score in an assault on a vehicle as close range meltagun hits (Penetration S8 + 2D6).
However, melta bombs need to be clamped in place before activating, so each model using them makes only one attack and doesn't count bonus attacks for charging, extra hand weapons, etc. Melta bombs can be used in a Death or Glory attack against a tank attempting to overrun.
Krak Grenades
Some troops are equipped with krak grenades, a special type of grenade with a shaped charge designed to penetrate armour, and (hopefully) stopping vehicles in their tracks. Troops equipped with krak grenades can use them to assault vehicles. Krak grenades give troops S6 for close combat hits scored against vehicles, making their Armour Penetration scores 6+D6. Krak grenades need both hands to trigger so models using them can only make a single attack and don't get bonus attacks for charging, additional hand weapons or anything else. Krak grenades can also be used to make a Death or Glory attack on an overrunning tank.