This achievement must be done in a multiplayer lobby that has at least one real person in it. Joining or creating a lobby with only bots will not count.
The solo solution to this grindy achievement is to try and find a lobby with a small player count (1-4 real players) and hope that they are bad at the game or not trying. The co-op solution, if you have a friend, is set up a 1 lap race in a private lobby and beat him/her over and over until it unlocks.
Alternatively you can go for it naturally, but it'll take a very long time, especially since most races with real people are essentially luck-based due to ramming and lag spikes.