There isn't much depth to the hood material really and dirt between the grooves isn't a major problem, if at all. The tar like deposits literally look like someone flicked them all over the roof with a paint brush, those will be my main concern in the sense that I don't want to use a product that'll dsicolour the marron finish. Serplus' wax acclaim shampoo has no affect on these no matter how hot or diluted, even when applied with a nail brush
Cheers for now anyway, at least I have the name of a finish protector for when I get to that stage.