Right i was wondering if it is possible to do any of the following:

GT5

Race a friend one on one or is it only the luck of the draw if you are in the same race

GTA4

go into the games such has mafia work or team death match with a friend or again is it pot luck if your in the same game

on gta, open a lobby or something and when you start the game others can join. I used to do it all the time with mates

GT5, im sure you can set up a private lobby and invite friends, not sure if prologue will have this though, but most other racing games do so dont see why it wouldnt.

GTA4, you can party up before you search for a game, just set up a private free-roam or something and then change the game type

hope it helps mate