You can get this in Career on a single Grand Prix race.
Within Career mode there is a tab for settings, click on this and then onto race setting and there is a slider bar to set race distance move this all the way to the right untill it says 100%.
In Grand Prix Mode again set the race distance to 100% and choose which track to race on.
Once you have qualified start the race but beware this will take the best part of 1 hour 45 mins to complete.
This does not have to be done in one sitting, you can use a mid session save and it does not effect the achievement, and you will also unlock "My Saviour" if you have not already done so.
You must finish the race DSQ or Crashing does not work.