Age limit is 18 for all programs but Venturing where the age limit is 21.
An 18 year old is considered an adult in the Boy Scouting program, he cannot take a 17 year Scout someplace alone.
Two registered adult leaders, or one registered leader and a parent of a participating Scout or other adult, one of whom must be at least 21 years of age or older, are required for all trips or outings. There are a few instances, such as patrol activities, when no adult leadership is required. Coed overnight activities, even those including parent and child, require male and female adult leaders, both of whom must be 21 years of age or older, and one of whom must be a registered member of the BSA.
You cannot transport someone else's kid alone in the car with you.
In an emergency you try your best to follow the rules, but emergencies are emergencies.
See the Guide to Safe Scouting:
--- In firstname.lastname@example.org, Michael Dotson <michaeldotson@...> wrote:
> We teach in YP that an adult is to never be alone with a youth. However, when, if ever, is it acceptable for an adult to drive a (single) scout to an event so long as the adult has the permission of the scout's parents? Or what about an emergency? Related, is there an age limit, that is, what if the scout is 17 and the adult is 18?
> [Non-text portions of this message have been removed]