A fork of Rural Dictionary
To be all over something, having it under control. Some say it is derived from Essex girls famed love of sex on a car bonnet, others from the female models at car trade shows that lay on car bonnets. (NB: UK Car Bonnet = US Car Hood) To be "On it like a car bonnet" means you are literally all over something, like an (Essex) girl on a car bonnet"
"Are you looking at this problem?" "Yeah, I'm on it like a car bonnet"