You will need to boost this with 7 other players as the achievement is very troublesome and complex if not organized properly.
First of all, you need to create a city with 5 short single lap tracks. Once you have done this, you need to search for a public domination race. Seeing as the games community is not active anymore, you will find a lobby to yourself. Once you're in a lobby, you need to invite the 7 other players.
At this point, load your custom city with the 5 short events you made earlier, and make sure before starting the race, every player in the lobby chooses the same car, it doesn't matter which car as long as it's the same otherwise the game tends to crash.
Once the race is loaded, have the 7 players let you, the host win all 5 races. Only the host will get the achievement, which is why this will have to be repeated 7 more times until everyone gets it. The same custom city you made originally can be used for everyone as well.