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(!) designs - All for the same car!
Then i saved designs 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 designs
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 designs and shared
them change to the other gamertag (or let your friend know your uploaded all designs) 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 TUNE achievement same way...
Any questions!? Message me or comment it...
Edit 1: Thanks to Spilner
Make sure the car you choose can be used with BOTH gamertags!
Edit 2: Thanks to Hypas
- "Made 35 layer groups and didn't work xD"
Some asked if Layer Groups work aswell in the comments. So we know now it doesnt!
Edit 3: Thanks again to Spilner
- "Go to 'Paint car' under customise and 'my designs' is the folder..."
For those who couldnt find it
(Also check/take a look at the comments!!!)