Ayy a fellow NZ'er, nice to see 
Agree about your style, interesting to see it become more stylised and less stiff, it's got a lot more character in it now. As far as critique goes, I'd love to see you put as much polish into the rest of your drawings as you do to the faces. You've got that bit down, they're cute and expressive, but the comparative roughness of the rest of the image usually lets it down. The key to a "finished" looking bit is clear values as far as I can see, and it looks like you're not as confident with what a random shape should look like as you are with a face. I can see you said you're trying to get better at them, but I'd recommend doing exercises instead of full paintings to practice. That way all your focus is on improving instead of having a nice piece at the end. Check out this pdf on value studies. Value is Form + Lighting, so thinking about how light interacts with the form and taking its base value and material into consideration, gives you what value to give it. Try:
- paint from life with values only.
- shade basic 3d shapes like spheres, cubes, pyramids, cylinders in different lighting situations. Keep those edges crisp. Expert mode: make them different materials e.g. stone, glass, plasic, metal, flesh, wood. (Don't worry about this until you're really confident with the normal shapes, no need to overcomplicate things, just putting down an idea I had)
- reference a colour photo and block in the areas of value, just focusing on large areas instead of detail. Then convert your reference to greyscale (in PS: Image > Mode > Greyscale), put them side-by-side and squint a bit to see how you did.
As far as your gestures / sketches, try getting the same information in one line instead of 5. It might be difficult at first because if you're only given one shot it's much more likely to be inaccurate, but if you stick at it eventually those one lines are going to go where you want them to and it'll look great.
Also when trying a new subject matter, I find it always looks way better if I try deconstruct some reference first. With the cars I'm not sure if you're going off reference - I don't recognise any of the models, but they might be from concept drawings/renders - but I'm guessing mostly no because of the proportions of the wheels. Cars have an anatomy all of their own to learn. Either way, again I'd say try to be more accurate with your lines, especially for inorganic subjects (vehicles, mechs, buildings, guns) because their materials are so rigid and defined. Scott Robertson is the main man I think of for industrial design, go check out a couple of his YouTube videos if this is something you're interested in pursuing further.
Well that turned into quite the essay, but hopefully helpful. Again I realy like your style and I'm interested to see where you go. Good luck my friend
