The Mighty Pen Tool
Lets start by creating a solid outline of the whole car.
Set the foreground color by choosing the 'Eyedropper Tool (I)' to sample the darkest area of the image. In this case it's close to black.
Next select the 'Pen Tool' from the toolbar. And up on the 'Options Toolbar', make sure the 'Shape Layers' option is selected as I have captured (in orange outline).
Then just start adding 'Anchor Points' at areas where you think they will require some adjustments.
TIP: Ctrl + (Plus Sign Key) to zoom in and Ctrl + (Minus Sign Key to zoom out on areas that need special detail. I do this a lot to achieve greater detail.
NOTE: By having the 'theimage copy' layer on top, the path outlines show through without disrupting the view of my next anchor point. Throughtout this tutorial, I will be toggling visibility of this layer a lot.
Connect The Anchor Points
After making your way around the minicar, connect to the first Anchor Point to create a solid shape. Then hide the 'theimage copy' layer to see what it looks like. (As I have captured.) Then lets start manipulating those anchor points to wrap/fit the minicar properly.
This is what the 'Layers Palette' now looks like, with the new Vector Shape Layer highlighed in blue. Also, if you click on the 'Paths' tab of the layers palette you can see the 'Paths' version of that layer.
More Tutorials: 
