I was watching X-Play today an this lady K. Holt was talking about GTA IV, "Pull out a pen and pencil for the ultimate cheat"
I will pull the rest up later, I lost the book I put the code in. So here is the ultimate cheat. Go to the tw@ internet cafe and go to the internet address bar and type www.whattheydontwantyoutoknow.com That page is a cheat codes and will show a detailed map telling you to find hiddin things like easter eggs , hidden vehicles , weapons ect.
The other cheats are
A sports car
Another Sports Car
A motor Boar
And A Police Helicopter.
You will have to use your phone to dial the numbers in for the code. (But I will bring them up soon )