I like the idea of this thread.
But with deep regret I have to raise some problems with Your works.
(I used samples from first two trucks from first drawing, but it applies to all of them, be it literally or "in principle")
1) Wheels - some of them (on trailers) don't have the black contour all around, which would be a must. Also, typically the "border" between tire and metal part of the wheel is also marked in black (generally exceptions exist, but usually when the wheel is simply too small). Also, the "holes" in the wheel (like on the wheels of IHC and Ford, but not on their trailers) rather shouldn't be all black.
Additionaly, the shading on the tires is IMHO not really "in the SB/FD spirit" (I'd suggest doing it along the lines of examples I provided, which is more the way it's typically done).
2) Under the fenders of Ford there are some strange pixels, which must not be there, simply a very dark (or some other, relevant color) area, not some random gathering of various 4096 shades.
3) "Double black lines" - something that should be avoided as much as possible ("holes" on the wheels in point 1 also come to this category) - either by using partially some other colour or tweaking the contour (of course, sometimes there's no way to avoid small amount of double black line, but most examples here can
be avoided). I'd suggest using black only for contours and filling it with very dark grey.
Also, besides double black lines (most striking examples are shown with red arrows) there are places where line should be black, but isn't (blue arrows - in fact there are more of such places I just didn't marked).
4) Door outlines. Here You have three approaches - black outline (huge doors on trailer from 1st drawing), dark-shade outline on Freightliner and seemingly no marking of them on IHC and Ford. Preferably choose one option and stick to it (I mean black outline or dark-shade outline, "no outline" is not an option, of course
5) One more thing that strikes me particularly on Ford - shading. Typically the brightest shade shows areas on which most of light falls (so those pointing upwards), middle those more-or-less vertical, and darkest on those where there is least light (so those pointing downwards). But shading on Ford has brightest shade used on sides of the body, but dark one on top of the hood (on the other hand, fenders are more or less fine)
6) And last but not least - templates. 1000 x 330 pixels are minimum
size and that's non-negotiable. Templates can be as big as necessary (within practical reason), but not smaller.