Looks amazing man. And the difference on your car was huge. Reminds me of when I got my VR4, it was red and had been sitting outside for 9 months when I got it. it was pink at that point.
But you were asking about what settings to use, and y8s had some good tips. But My addition would be shooting in shadow or at the magic hour (twilight).
What it looks like at twilight, light is diffused and smooth.
Overcast, light comes from above but not as harsh as it would in the clear because the clouds diffuse the light. That way you get a well lit car with good emphasis on body lines.
Shadow, Notice on the roof how light colored objects reflect and show off the paint, you could easily point one strong light at a wall that would get reflected in the paint. So the wall is lit up and not the paint directly.
The last tip is something you can use every time, The first 2 are just really good conditions when you get them. If you don't have an external flash you could also just bump up the power of your internal flash and use a mirror or just anything white or reflective to bounce the flash to the ceiling. Lighting up the entire ceiling or just parts of it will do a LOT.
Not trying to jack the thread, just trying to help you show off your own work even better. I wish I knew how to detail like you guys do.