I was cleaning my Skoda and noticed spots on the bonnet

Have similar marks on my doors but it was due to sunscreen from the kids. Never did get rid of them. Yours may be from a vehicle in front leaking hydraulic fluid/antifreeze etc thats soaked into the paint. I read that meths or a car cleaning wax polish/colour restorer might help. Try on a hidden place first.

Alasdair

6 hours ago, Alasdair1 said:

Have similar marks on my doors but it was due to sunscreen from the kids. Never did get rid of them. Yours may be from a vehicle in front leaking hydraulic fluid/antifreeze etc thats soaked into the paint. I read that meths or a car cleaning wax polish/colour restorer might help. Try on a hidden place first.

Alasdair

Hmm has me thinking if it could do with the feces I prefer to store on my bonnet

11 hours ago, Mltw said:

Hmm has me thinking if it could do with the feces I prefer to store on my bonnet

Could be. My dad always washed bird droppings off as he said it was caustic and would damage the paint. A  friend has a car similar. She rarely washes it and its usually either covered in bird droppings or sticky mess from greenfly from the trees she parks it under, Its a standing joke. We reckon if she leaves it any longer it will become part of nature. Her previous car even had a tree seedling growing in the gap for the sunroof.

Alasdair

@Mltw Welcome.

How long have you had the car and is the first time when washing the car that you have noticed these spots? 

Has the car still got the original paint 20 years on and wash the last cleaning / detailing any different from what was done previously?