If your tail light/indicator lenses have faded and they have lost their bright colours, here is a hint that will at least get you through rego.

Paint the insides with bright red or orange nail polish. Nail polish is translucent so the light will shine through and it will restore the colour for a while, until it inevitably fades.

This can be done very easily to non-VW cars simply by removing the screw in globe holder and using a long handled artist's brush to apply the nail polish.