EMRE HUSMEN
PHOTOSHOP RENDERING

The final result Emre is able to achieve here is a good example of how a good image manipulation program such as Photoshop can be used to emulate the super gloss feeling of a traditional airbrush rendering.  Crisp, sharp, full of detail and very, very shiny!

Create more body details with the same grey tones.

Now, start using the Dodge and Burn Tools! Use 200-300 px "airbrush" with 20-40% exposure. Darken the lower parts and lighten the upper parts. Also select a part on the windows for shining; open a new layer above the window layer and use a white airbrush to fill it a little bit (do not fill it all). Darken the headlight.

Find some nice rims from reference pictures (or you can create your own). Cut and paste it above the body layer and play with its colour and contrast. Select an ellipse on headlight layer and fill it with white. Give it some outer glow effect. Colourize the windows from Hue/Saturation menu (press CTRL + U).
 

Make a simple background with black and white gradients.

Decide where the light will come from. Duplicate your rims two times, each, use the ellipse layers under the rims and create your tires with using Dodge and Burn Tools.

Colourize the body with a matt tones (use the Hue/Saturation menu).

Put more details on your design. And now it's time to give some shining to your car. Open a new layer on the body layers; select & airbrush it with white. Complete everything except your final body colour. Merge layers from the lowest body layer to the top. Keep the shadow and background layers separate.

Duplicate the "merged layers" two times. Colourize them with blue and yellow tones (separately). Now, you have to use airbrush eraser to remove the mixed parts of those colours. Use the "overlay" effect (under the layer effects menu) for both of them. Put some white dots on the edges to make the shining more realistic (on another layer). Lastly give some reflections to the car and the background with layer effects menu..