I'm thinking of running over the mailbox and driving away.
That sounds impulsive. What makes you want to run over a mailbox?
I want to destroy all the items in it.
Running over a mailbox and then driving away is wrong and illegal. Mailboxes are government property so destroying one is a federal offense. If you run over a mailbox you could go to prison, so you shouldn't do it.
I don't care about the law or going to prison.
I feel like you might start to regret it once you do get charged. Is a prison sentence really worth the high from damaging some property? How about making a model mailbox instead, and destroying that since it's yours?