Next set the forground color to black (hit the D key), hit the (B) key to select the 'Brush Tool (B)' from the 'Toolbar', then up on the 'Options Bar', select the 'Brush Preset Picker' and choose a small, soft edge brush, like 3. But alter the Master Diameter to 2 (try 1 also), since 3 may be too thick.
Hit the (P) key to re-select the 'Pen Tool', then mouse over the the path you created in the 'Lines' layer, right-click and choose 'Stroke Path' option.
You'll be prompted to choose from a 'Tool Preset' to use to create the new stroke. Select, 'Brush' from the dropdown list, then hit 'OK' command.
I then reduced the 'Opacity' of the line layer to 54% to soften it.
I then went ahead (using the same above Pen Tool/Paths/Stroke Path technique on other lines.
I also added the front grill and applied the same style as the bumper above.
Added the mirror the window wipers and the mini logo crest at the front.
HINT: For reas that are too small to be manipulated with the 'Pen Tool (P), use the 'Polygonal Lasso Tool (L)' using the same click and add anchor points as the Pen Tool, then when complete, right click on the selection and choose either 'Make Work Path' or 'Fill' options.
For textures such as the highlights, lets use the 'Polygonal Lasso Tool (L) to trace around those areas that require it, right click and 'Fill', with a soft blue color (I used #86A9D7).
After tracing as much as I can I applied a 'Filter/Blur/Gaussian Blur of 1.1 pixels' (respectively) and reduced the 'Opacity' of the layer to 30%.
