Possible Clues:

• He slept for 20 years
• Long sleeper had to rent carrier with shellfish
• Character associated with 'The Big Sleep'? Yes and no
• Big sleeper causes damage, then railway carriage runs out of line
• Washington man in rush getting vehicle to indicate extremely late
• Ne'er-do-well who stayed out for a long time?
• Short story by American author Washington Irving
• Person oblivious to social change
• Rent vehicle plant that was dormant for a long period
• Someone who sleeps a lot (for 20 years?)