This is straight forward all u need to do is:
open the image without the car bonnet
copy the image with the bonnet and paste it as a new layer
set the saturation on the hood/bonnet vents to 0 and keep the lightness the same
cut out the bonnet/hood pins and paste on a new layer
now go to the layer with the bonnet/hood and set the blend mode to luminance
set the opacity to 65%
and your done 2 minute job
you can remove the rest of the body work and leave just the bonnet/hood but for a quick application there's no need
here is what the image will look like
