^ That was shown in the 4th film.. I saw that.
Spoiler:
But we don't actually know if the car flipped since we didn't see it "actually" happen. All we know is that the guy um.. Phoenix? said that something about shooting her and all he remembered was her body burning.
But in fact how do WE really know that he was telling the truth? IMO they should bring her back in the 6th film with some storyline like... She didn't die, that guy was just lying.. and maybe she was still alive and just got kidnapped or something for some sort of information.
^^ If that actually happened in the 6th film then Letty and Dom could get back together! Squeeeeee!!!
OR... Unless at the end credits of Fast Five they had proof that she was dead...
Did they have proof???