Nacho,
Killer work, my friend. I agree with you about the finish/condition of the cars. I don't think anyone will question you build techniques
From the pictures I've seen, most body panels don't fit very well, and the paint jobs are ok at best.
I have a Tamiya 1/12th Ferrari 312T driven by Niki Lauda that I have been doing some research on, and one thing I've noticed is that nothing fits
So I will do my best to make the car look nice, but I won't be filling any seams like I do on my aircraft kits.....
Great work,
Cheers, Ian