way-back
in any vehicle with 2+ rows, any seat or area behind the second row of seats, typically, cargo space rather than seating
Example:
on vacations, mom and dad took turns driving, my 2 brothers rode in the backseat, leaving me stuck in the way-back with the dog.
on vacations, mom and dad took turns driving, my 2 brothers rode in the backseat, leaving me stuck in the way-back with the dog.