I'm a bit late, but these are called "Normal Maps" I think.
YOu can create them using this webstie for example : http://cpetry.github.io/NormalMap-Online/
Just drop you image in there and it'll create the normal for you, and there are some options too.

I know I'm a bit late, but I could help you if you want.
I have already made some engine sounds (including a Lambogrghini one).

Just join my Discord server so we can talk about it : http://discord.gg/KXkzqBc

I made some engine sounds if you want to check how they are made.

Are you sure you made the sounds LOUD enough ?
Are they at the correct frequency / compression / length ?

Making engine sounds is possible, just look at the ones I made. But you can't make a custom vehicle sound off of a YouTube video. The .wav files you need to create create have to sound really clear and be a cprecise length, frequency and compression. It's LONG to make a good-sounding sound mod, but it's possible.

Eh beh, ça fait plaisir de voir des vidéos de mdding GTA V en français ! Et c'est super