The matchmaking in this game is dire and after having spent 4 hours trying to get into a public PVP lobby in an attempt to get this achievement, after finally getting to work as a team, we decided "someone" should write a solution to help others on TA.
The following is what worked for us as a team of 8.
After trying many different ways of searching for each other in the public PVP lobby, all without success, we tried getting the achievement in a private lobby instead. (This does not work, but may have helped match us later).
Here are the steps we took.....
First off we got 2 people into a private lobby, then invited in the other members of the party, so all 8 of us were in the lobby.
Next we arranged ourselves into crews, then made sure that each crew was on the same colour team.
We tried a couple of races to see if we could get the achievement in the private lobby, but that didn't work, so we quit out and returned to the map.This is probably the most vital element
The game returned all of us the to the same PVP location on the map, so we could all see each other's names, although the cars were invisible for some.
We then tried to search for a public game and got into a lobby straight away. Instantly, no waiting, no count down timer, immediately.
We completed a race making sure that we met the finish 1,2,3 conditions, but to be extra safe we finished 1,2,3,4 and also made sure that the losing team finished so there were no dnf's.
After both teams had gotten the achievement, which pops at the race results screen, we backed out of the lobby and tried entering again to test the method and again were instantly pulled into the Public PVP lobby.
So it seems the important thing is, to all be at the same PVP location, in 2 crews of 4.Extra Notes
I think the 4 vs 4 is important, I had tried being at the same location in a previous 3 vs 3 session, but that did not work.
Before getting it to work, we had tried searching as 4 x 2 player crews, searching as 2 x4 player crews, searching individually, making sure each crew belonged to the same faction, different PVP locations, nothing seemed to matter or work, until we went through the process mentioned above.
As I say the important thing is probably to be in the same location, but we did feel that maybe as we had just all been matched up in a private lobby first, maybe that had helped the game match us again, but we weren't sure, so I've added in all our steps, just in case.
Hopefully that sheds some light on this and help's others get the achievement easily, although no doubt it will lower it's ratio, the fact our success could save many hours of others peoples time, it had to be worth writing a detailed solution.
Good Luck and thanks to the other members of the session, who deserve credit for this solution as wellHayz7890IanK1987
(extra proof reading credit)se7ense7ensR49WAFFLETRAIN7997MarekVitODYsseyGrimwallSlimypickel4