getting there mate!
#1 the car is the centerpoint of the pic mate you need more scenery/background around the car, i know brisbane has some good photo spots get out there and find/abuse them
#2 under exposed on your car you want it the other way around try using some artifical light to make car brighter a little (not the flash)
#3 desaturated images work great in a enviroment that isnt exactly exciting this one is a good shot
#4 Same as above but yeh boring scenery around the car works better desaturated
#5 cool outline of the car you got going but i think you need to do a little longer exposure on this (not much more) and maybe wait till the sun is right down, capture the colours of the sunset, too much sunlight is bad!
#6 The sun really ruined what could have been a good angle shot, next time wait till the sun is out of the window and it should light up the car a little bit more (if u dont want too much detail on the car and just want outline use a quicker shutter speed) by the sun being lower it will outline more of the car not just the roof
dont take this a rude critism mate cause not trying to be just trying to give ya some pointers