WRC: FIA World Rally Championship

You can easily get this by going for Once you make it to level 8 (Having finished every event for levels 1-7 prior to this) you'll only need a few more stages to have raced on to have raced on all 78 stages, luckily these are in with the first 7 stages of the Level 8-1 event.
Will unlock once Mexico stage 3 has finished

I will provide a list of every stage so you can check them off if you wish:

Corona Rally Mexico
Alfaro 1
Ibarilla 1
Guanajuarito 1
Alfaro 2
Guanajuarito 2
Ibarilla 2

Jordan Rally
Kafrain 1
Mount Nebo 1
Yakrut 1
Kafrain 2
Yakrut 2
Mount Nebo 2

Rally Of Turkey
Darlik 1
Gocbeyli 1
Deniz 1
Darlik 2
Deniz 2
Gocbeyli 2

Rally New Zealand
Springfield 1
Whaanga Coast 1
New Franklin 1
Springfield 2
New Franklin 2
Whaanga Coast 2

Vodafone Rally De Portugal
Vascao 1
Estadio Algarve 1
Almodovar 1
Vascao 2
Almodovar 2
Estadio Algarve 2

Rally Bulgaria
Batak Lake 1
Sestrimo 1
Slavovitsa 1
Batak Lake 2
Slavovitsa 2
Sestrimo 2

Neste Oil Rally Finland
Jukojarvi 1
Leustu 1
Himos 1
Jukojarvi 2
Himos 2
Leustu 2

Rally Of Germany
Weinhugel 1
Sonnenpromenade 1
Stadizentrum 1
Weinhugel 2
Stadizentrum 2
Sonnenpromenade 2

Rally Japan
Nikara 1
Iwanke 1
Sapporo 1
Nikara 2
Sapporo 2
Iwanke 2

Rallye De France
Vallee De Munster 1
Klevener 1
Le Firstplan 1
Vallee De Munster 2
Le Firstplan 2
Klevener 2

Rally RACC Rallye De Espania
El Priorat 1
Santa Marina 1
La Serra D'Almos 1
El Priorat 2
La Serra D'Almos 2
Santa Marina 2

Wales Rally GB
Sweet Lamb 1
Halfway 1
Margam Park 1
Sweet Lamb 2
Margam Park 2
Halfway 2

Rally Sweden
Viggen 1
Sagen 1
Likenas 1
Viggen 2
Likenas 2
Sagen 2

You can look in the Statistics menu to see how many of the 78 you have raced on (Page 1 under 'Different Stages Raced')

The other solutions are good, but if like me you shot through the 'road to wrc' doing the bare minimum races and you find you have a couple of stages left out of the 78 stages, but don't know which ones, go to the main menu, 'statistics', 'time records', and read the scrolling text at the bottom of the screen for each stage. It'll tell you how many times you have raced each individual special stage. Whichever ones you haven't done, make a note of and go do in 'single player', 'single stage'. This'll mean you aren't having to wait for it and have it randomly pop whilst you complete all the objectives.

Just play the game normally on Road to WRC and you will receive this achievement almost at the end of the 1st tournament of the 8th level.
If you are having problems with this game, lower the difficulty as it does not affect achievements.