Metallic paint is a no cost option on all Motability cars Lou, so I don’t know where that’s come from. We’ve had metallic on every Motability car and never paid a penny for it. We also placed an order for a new Motability car (BMW) very recently and metallic paint was added at no cost. Some manufacturers have premium paints that are more expensive than normal metallics, but you just pay the extra cost (only) above the price of the normal metallic paints. Volvo charged Motability customers for metallic paint for a while a year or two ago but, as far as I know, that was just for a short period of time and they reversed the policy.
Edit – I don’t know anything about grants though. I suppose that it could be that those in receipt of grants can’t add metallic paint, but having no knowledge of this aspect that’s just a wild guess. Others will clarify.