You can even get this achievement by yourself. All you need is a second gamertag!
(or friend that may helps you)
What i did was following... I have created 35(!) tunig setups.
All for the same car with nothing really changed
in the settings.
Took the cheapest car and automaticly tuned it within its own CLASS (for example E150 to E200)
Be sure the car you choose can be used with both gamertags!!!
Then i saved those settings like for example...
A1, A2 ,A3 ,A4 ,A5
B1, B2, B3... and so on and so on ;-)
(A1-5, B 1-5, C 1-5, D 1-5, E 1-5, F1-5, G 1-5) makes 35 tunig setups
Now it works like this:
35 DOWNLOADS give you 17.500Cr
35 LIKES give you 35.000Cr
Thats 52.500 Credits at all and the achievement unlocks immediately...
Now after youve created the 35 setups and shared
them change to the other gamertag (or let your friend know your uploaded all tunes) and simply DOWNLOAD and LIKE them ALL!!!
After that again switch to your main gamertag, log in, start the game and the achievement unlocks ;-)Note this works for the DESIGN achievement same way...
Any questions!? Message me or comment it...
Edit1: Just a note by HolyHa1fDead
: "I created zzz01 - zzz34. You don't need to tune your car, just save and share." - Thanks for this...