This is a 1965 Ford Van I drew in a simple graphic style. I tried a different approach this time and I think it turned out pretty good.
My usual approach is to create a set of different gradients using various shades of the body color for the highlights and shadows. Instead, this time I drew all the shadows in black and all the highlights in white, then layered the body color over top. By adjusting the body color using the transparency setting, the white highlights now appear to be a shade of the body color.
The result is that the entire van color can be switched to another color just changing one solid color instead of changing and adjusting a bunch of gradients.
Below are examples of the van in orange, blue and red. I changed them all just by selecting the body color and changing it to another color.
The shadow and highlights are set up for light to medium colors but maybe with a few adjustments it could work with dark colors too.
Take care, greg