I have a 8 inch scratch on the front wing of our '5. The car is gloss black and the scratch doesnt seem to have gone down to the metal its just taken the surface off the paint. Its to deep for sctach X or T cut though as you can kind of feel the glitch in the paint if I run my nail over it.
This sounds a little like the langka paint repair kit I got through a group buy on one of the MX5 forums (a long while ago). These work on the basis that touch up paint is softer than factory. You’re supposed clean the area, plut on a blob of touch up paint, and then let it dry for a day or so. You then take the supplied applicator, which was no more than a piece of plastic, with a lint-free cloth tightly wrapped on it, put a bit of their magic stuff (blob eliminator) on in, then rub the blob like furious, then buff off. Can remember if the final coat of stuff was some sort of lacquer or not. Did it work? Kind of. If you let the paint dry too long, you didn’t get anywhere. If you didn’t let it dry long enough, you merely rubbed off the touch in paint. The langka polish didn’t harm the factory mica paint. I managed to get a couple of scratches looking decent. Typically, the videos of Langka at work, online, are too good to be true. There was one posted by a US Mazda3 Club. http://www.langka.com/
I think the secret is the plastic card.
I might try this Aldi stuff, as I’m a sucker for cheap garbage, which might work, and I have a car covered in scratches and chips.