This is unlocked via progression in Career mode. Specifically this is for progress through the Rally Discipline. This one is a long one folks...
As the achievement says, you must make it to "International Rally R-1"
To do this you must obtain the necessary medals for:
1. National Clubman (1 Event, 1 Stage)
2. National Rally B (1 Event, 2 Stages)
3. National Rally A (2 Events, 8 Stages)
4. International Rally R-3 (6 Events, 28 Stages)
5. International Rally R-2 (4 Events, 32 Stages)
After completion of International Rally R-2, International Rally R-1 will unlock and so will your achievement.
Rally R-1 has another 2 Events, 30 Stages