From the main WRC menu, choose SEASON, not CAREER.
Create it with any settings you like, it doesn't matter, but start in the Junior WRC class.
1 At the first service station, allocate your tyres - putting them all into one type is quickest - then press confirm.
2 Now scroll down the left hand menu, and choose Quit Rally - NOT quit game!
3 You'll immediately move to the next rally without any loading. Repeat from Step 1 until the five rally season finishes. Achievement unlocked!
If you continue to the next season and pick a different team, and then do that again a third time, you can also unlock the following achievement too in about seven minutes: