As you've not done much there isn't much to screw up...the wheels are nicely done, the bg change is well done, the whole image looks clean!
But a few things: if the ground is this wet (even if its wood) there should be very slight reflection of the car on the ground. The rain drops on the car would be a cool idea but as they are soo blurry its just ruins it completely! Let us see the rain, like this it looks as if the original image was about 150*150pixels and you tried to enlarge it! Just little details but rain is very difficult soo dont worry too much...One last thing and this was an issue with your DS3 chop as well, the car is very blue but the bg and the ambience around the car is all very orange, make sure next time to watch out for this, as though the car fits the bg angle-wise the color differences make it very odd! This is especially ruined by the window being extremely light blue which to me stands out too much in comparisson to the dim/orange bg! oh and lastly why is there a rear window on the other side of the car when the Caddy is actually a van?!
overall nicely done, just next time if you do soo little to the car make sure everything is done perfectly!
but the colors are better imo