They were kissing your car obviously, or they thought it was a massive lolly..
Metho MIGHT work, other than the fact that they evaporate completely in a matter of minutes..
But the vaseline+capsaicin idea would work pretty well, in fact, any oil that coats thinly and evenly would work, then the kids rub their eyes, would be fun times... you might feel like killing them, but violence is not the answer...