Quickest way I found to get this was start a career mode, start in WRC3 as a manufacturer team, set difficulty to 50, rally length to short and damage to no damage.
Finish every stage as high up as you can, it's fairly easy at this difficulty so you should be able to win with ease. Work you way up the ranks to WRC2 and then WRC, half way through your WRC campaign you should unlock this achievement. I'd also recommend you spend some R&D points in the Team section, particularly the ones that increase XP and double XP, it'll help you to get this achievement a little bit quicker, I can't remember what they're called at the moment.
If there's faster ways let me know and if you downvote, please let me know why.
Thanks.