Qualcuno ha versato olio sul mio noleggio quando ho visitato l’Islanda l’anno scorso

What exactly did you experience?
A random act of vandalism?

Are you sure you didn’t drive through a Diddy party?

That sucks. You can go to Löður, a self service car wash. Spray the car with tar remover and use the foam brush. Then wash it off with the power washer and it should come off.