Thanks! To be fair, I wouldn't recommend anyone to program this the way I did there, it is incredibly not optimized (basically simulating one raster, aka one horizontal line of the screen, as one object in GM) but I used Lou's Pseudo 3d tutorial as a base for it (tweaking it slightly to achieve the results I wanted in the end) : http://www.extentofthejam.com/pseudo/
I actually changed it a bit for a future project in the works, not a racing game but still using the effects in some places! :)