First up - the backdrop and wheels seem to fit very nicely
Good work there
It's got some potential to look really cool with the smoothed styling too
A few tips that may help your brushing:
- Use the pen tool for ALL selections - set feather to 0.3px. This avoids sharp jagged edges to selections, and the sketchy lines in places like the edge of the trunk
- Look at the reflections on the base - try and work out what each part is reflecting, then apply the same idea to your brushing
- Think about your door lines and the shapes that would cause highlighted- the highlight is on the wrong side of the line - a bright line is reflecting off a flat panel at the moment
- Be confident to add bigger contrast between light and dark shades - even with matte paint
- Consider using a mixture of c+p and brush. The best chops are not 100% full brush
Use differing brightnesses of colours to show the shapes - not white highlight lines:
Good luck