Ah. I found out what the issue was.
Issue: I'm an idiot lol.
I exported it from aCar, edited it, then tried to give it back as a CSV file but what i should of done is giving it back
AS an aCar file. Did that and it worked.
YAY!
So this thread can be closed. Thanks for your help. Can't wait for the aCar/Fuelly merge