Hi Tom very nice work can't wait to test these on track
! I just noticed the front bumper in the render of the zr1 I think the black artifact comes from 2 bumper copies overlapping but not sure... It might cause you weird display in the game too later on.
By the way if you want to make renders of your cars you can use cycles render, It is a bit easier to set up and gives more light to the shapes. What I usually do is put a ground plane with a dark and rough glossy (0.85 +) and put a plane with a white emit on to of the car. For the body paint I use a mix shader with a diffuse as color input and a glossy with 0 roughness and plug a layer weight (put facing at 0.12 and use this input) in the mix factor. This will give you nice renders and I also use the reflections to make smoother topology. All that is not necessary but adds a bit of wow factor to your models
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Anyway nice job !
Merry Christmas to all of you
J.J.