The Ravenwing

Source: Codex: Dark Angels, p. 5

Dark Angels of the Ravenwing practise and train continuously in the use of the vehicles they ride. They may re-roll the dice if they fail a Difficult Terrain test. In addition, they are trained to 'jink' their vehicles from side to side. This allows them a 6+ invulnerable save against any enemy shooting attacks as long as they moved in their previous movement phase. This save may be taken instead of their normal armour save, not in addition to it. Land Speeders and attack bikes are allowed to take this special saving throw, even though Land Speeders are vehicles and therefore do not normally get a save.