"A turbo engine with no boost is not a turbo engine," he joked to the German media.
Monaco was actually Vettel's 100th grand prix for Red Bull, and the last nine of 2013 he won on the trot.
But after Sunday's race, he couldn't wait to get out of the Principality.
"How do I get out of here?" he asked reporters, reaching hard for his customary humour. "I don't have a boat!"
But not much earlier, his in-race frustration on the radio was obvious. "Come on guys," he pleaded to the pitwall. "I mean, you've trying everything."
At the very same time, team newcomer Daniel Ricciardo is sweeping up the plaudits and making Vettel look like Red Bull's 'number 2'.
"Every champion goes through a phase like this at some point," former F1 driver turned commentator Martin Brundle is quoted by Germany's Die Welt.
"It seems as though he has inherited Mark Webber's car," the Briton added, referring to the fact that, in the past, it was usually Vettel's teammate with the lion's share of problems.
Vettel agreed: "It's always something different going wrong, but it can't go on forever."
Mercedes team chairman Niki Lauda admitted he feels for the beleaguered champion.
"This can happen when a team is trying so hard to come back, but unfortunately it's always happening to Sebastian.
"When things go wrong, they go wrong," the triple world champion told RTL television.
The German news agency DPA quoted Vettel as saying: "Sh*t happens. We move on."