Here's how Vinny saves Brian's life in Wrath of the Century.
[we now come to Quahog and we see the Griffin family are watching TV.]
[Meanwhile, Brian is outside, setting up a goal post]
Vinny: [comes out and then notices a truck coming towards Brian] BRIAN, LOOK OUT!! [shoves him out of the way and is hit by the truck!]
Brian: AAAHHH!!! VINNY!!!
[everyone else rushes out]
Lois: OH, MY GOD!! VINNY?! VINNY, CAN YOU HEAR ME?!
Peter: Holy crap! What the hell happened?!
Brian: CALL AN AMBULENCE!! SYLVEON, CALL AN AMBULENCE!!!!
[we are now at the Quahog hospital]
Meg: Mom, is Vinny gonna be okay?
Lois: I don't know. But this is the best hospital in Quahog, Vinny's getting the finest care there is.
Brian: Oh, God. Oh, God.
Leafoen: Mom, do you think Vinny will come out okay?
Sylveon: I don't know. Because, Brian's being stressful.
Stewie: He had to share the ambulance with a chicken.
[Peter sees a chicken carrying it's head]
Peter: Aren't you supposed to be running around?
Chicken: Don't talk to me. You have a bad reputation in the chicken community.
[then the doctor comes in]
Lois: Oh doctor, how is Vinny? Is he gonna be okay?
Doctor: I'm so sorry, Mrs. Griffin. But Vinny's injuries are too severe for us to save him. I don't know how much longer he has, so I sugest you go in and say your goodbyes.
[everyone is shocked and sad to hear this, but Brian is worse of all]
[they then go inside and come up to Vinny]
Lois: Oh, my God. Vinny!
Peter: I..I can't believe it. Y..you're really..
Espeon: No, no! It can't end like this!
Stewie: Dammit, Vinny you can't die!
Brian: Yeah, man! We were gonna go on many amazing adventures you and I! And we're borthers! You can't leave me, Sylveon, or Elsa! Not even Anna!
Sylveon: Please... don't leave us.
Lois: [gasps] You guys, I think Vinny's trying to say something.
Galceon: I think he is too!
Vinny: You gave me a wonderful life. I love you all. [he smiles but then he closes his eyes as the monitor beeps]
Doctor: I'm sorry, he's gone.
Chris: Oh, my God. He's?
Lois: Yes, Chris. I'm afraid... I'm afraid that our Vinny is dead.
[sad music plays as everyone sorrows for the loss of Vinny]
Sylveon: [has a group hug with her children]
Brian: He saved my life. [joins the hug]