Start with our photo. I took this one down by the beach. (Thanks George for getting me access to this car).
Using the rectangle marquee tool, make a selection around the top part of the image. Starting at the desired reflection point (bottom of the wheels)
Press Ctrl/Cmd+J To copy the selection to a new layer
Press Ctrl/Cmd+T for free transform
Right click and choose Flip vertical.
Drag the flipped layer into position so it looks like a mirror image.
Choose Filter>Blur>Motion blur
Set the angle to 90. This will give it that watery effect.
Thats the basic effect. To add a variation, let’s fade it.
STEP 7 – VARIATION 1, FADED REFLECTION
Add a layer mask by clicking the layer mask button in the layers panel. (the rectangle with the circle in it)
Choose the gradient tool and set it to foreground to background and linear
Press the D key to reset colors.
With the mask selected, drag the gradient to blend the reflection.
STEP 10. VARIATION 2, PUDDLE.
For the second variation, a puddle, pick back up at step #6.
With the lasso tool, make a selection in the shape of the puddle.
Make a new layer (+ button in the layers panel)
Fill with background color. Press Cmd+Delete on mac Ctrl+Backspace on Windows.
Drag the puddle shape below the reflection layer in the layers panel.
Hold down alt/option and move the curser between the puddle and reflection layers in the layers panel. You will see the cursor turn into an arrow. Click
Now the reflection is inside the puddle. This is a clipping group.
Choose Filter Blur>Gaussian Blur on the puddle layer. This will soften the edges and blend in the puddle. The amount will depend on the resolution of your image. Choose the amount of blur that looks natural to you.
Lower the opacity of the puddle layer to suit your tastes.
And the result.
For additional realism. Duplicate the puddle and enlarge it.
Darken the copy to make it look like a stain on the ground where the ground is damp around the puddle. (I also masked out the stain where the puddle is, so that the puddle itself doesn’t get darkened).
Don’t forget to mask out the bottom of the wheels if you get bleed-through.