Hi,
I'v got a silver mk4 with over 100k on the clock, so you can imagine what the paint work will look like. I sometimes feel like I'm polishing a turd

but I feel I do a pretty decent job!
The previous owners did and my self clean it atleast once a month. However, the bottom of my front 2 doors and all over the back bumper and on the front bumper there are tiny little bits of what I think it tar. I scratch it with my nail and it smears and leaves a worse mark than before, so I just sponge over them and just leave them. I have used a clay bar kit on it once but it didn't seem to shift this tar.
Could anyone suggest and sort of cleaning solution to help remove these marks?
Cheers, Si