Here's a '37 Willys I shot last night. It seemed to be too pretty to just leave it in the parking lot!
1. Make a selection of the car & one of the windows & save them in the Channels Palette as a Channel mask. (Look at the buttons at the bottom of the Channels Palette).
More about Selections - what I like for objects with hard edges: Selecting areas in PhotoShop
Click the Palette Tab to return to the Layers Palette. 2-click on the Background layer to unlock it. Rename it or go with the default "Layer 0" name.
Recall the main car selection.
Layer> Add Layer Mask> Reveal All
Edit> Fill, with black.
Now the unwanted background should be hidden.
Ctrl + D to remove the selection boundry.
2. Shows the Layer mask. Other layers "Eye's" are off.
Layer Masks - What the Thumbnails mean
Free Layer Mask Tool for Photoshop Elements 6, 7 and 8
The Essential Approach to Masking in Photoshop
(NOTE: You could just drag the background of your choice from another pic in, instead of making the gradient background.)
3. Select a color for the Gradient. I used one from the car.
Layer> New Layer. Drag it below the old Background layer.
Select the Gradient Tool & the Reflected Gradient & drag a diagonal line across the car. Play with it 'till you get it where you want it.
4. I recalled the windows selection from the Channels Palette, Edit> Copied a selection of the gradient layer, & pasted it into a new layer.
It looked to bright to be a background seen through the windows, so Layer> Adjustment Layer> Hue & Saturation & I set the Sat at -50.
Then I added a new layer between the car & the gradient & painted in a black shadow with the brush opacity at 11% to give me more control.
Done, unless you decide to retouch the car. I decided to do a bit, so I made a copy of the car layer & did the retouching on that.
You can see the final result here:
Blown '37 Willys - A Beauty with a Beast!
Have fun with it!
One thing I didn't mention is that an Adjustment Layer (AL) affects ALL layers beneath it. You can avoid that by Grouping (locking) the AL only to the layer below it by Alt-clicking between the AL & the layer below it. You'll see a little down arrow in the AL after you do that. (Not shown here.)
A Group can be unlocked (guess what!) by Alt-clicking between the layers again.
EDIT2: I'm told that this is a Clipping Mask, not a Group.
This is a simplified version of the Layer & Channel Pallets to illustrate using a Layer Mask to hide part of an image. Normally, I would have put the sky image over the P-51 image. Dunno why I did the reverse here.
Mustang & B-17 + PS - Post #26
Doing cars is comparatively easy. Here's some incentive for the bike guys:
EDIT3: Mark (lambocars), has a similar tutorial on his site here: CREATING A PHOTO FROM A SHOWROOM SNAPSHOT
More links below.