Iron Man: Pretty sure Stark has never died. Captain America: Cap was killed when he was shot after losing out the long-drawn registration battle against Stark and the government (the conclusion to the Civil War arc in Fallen Son: The Death of Captain America). But he wasn't actually dead.
Minors (individuals under age 18) and people who are mentally incompetent do not have the legal capacity to enter into contracts. All other people are considered to have the legal capacity to enter into contracts. In New Mexico and most states, the legal age for entering into contracts is 18 (see NMSA Â§28-6-1). A contract between a minor and an adult may be cancelled upon request of the minor, but is binding on the adult.
No a minor can not sell a vehicle in the USA. You must be over 18 years of age in most states but the age to enter into a contract will vary from state to state. Check with your State Dept of Motor vehicles, or call your city govt.