Not a bad attempt, just a few things could be improved.
The selections aren't very good, try and start to use the pen tool instead of the lasso one.
The shadow is off in places and very strong and sharp.
Tutorial
The door lines are all one tone/darkness everywhere they have been created. If you have a look on the base they kinda disappear in places, so try and get them similar to that.
Tutorial
Wheels seem to be the right size and placement but they could do with some shadows between them and the arches.
The background is a different angle compared to the car. (Car image has been taken at a lower angle to the background.)
Instead of trying to randomly make up reflections and the lighting, try and find a donor car that is similar shape, colour angle and try to brush those reflections onto your chop, whilst getting some of the colours off the donor's paint for yours.
Tutorial
I really like the style with the wheels and colour you have chosen!
Those are probably the biggest things that could be improved. Just take your time and look at a few tutorials in the
tutorial section and I'm sure you will improve!
