Hulkenberg says his last-minute return to F1 at the Eifel GP was 'wilder and crazier' than Silverstone earlier in 2020.
Hulkenberg was called by the team on Saturday morning after regular driver Lance Stroll felt unwell.
The German rushed to the circuit, but he wasn't able to participate in FP3.
Having been approved to drive by the FIA he jumped into the car for qualifying. Clearly struggling to adapt at such short notice, he locked up several times.
He eventually had to settle for 20th and last place, but he was only two tenths shy of the Williams of Nicholas Latifi and the Alfa Romeo of Kimi Raikkonen.
Hulkenberg replaced the COVID-positive Sergio Perez at Silverstone for the British GP weekend, but had more notice on that occasion.
He went on to qualify third on his second outing at the 70th Anniversary race at the same venue.
"It was even wilder and crazier than last time," he told Sky F1. "I was in Cologne, which is kind of an hour from here. I was due to come here this afternoon anyways, and I was going to do some TV stuff for RTL tomorrow.
"I was sat with a friend having a coffee at 11am when when I see that Otmar [Szafnauer] rings me and says, 'Hulkenberg hurry, we need you here.' And I stepped in the car and came here.
"And the rest is history, we saw what happened now. Obviously it's the 2.0 return, in a moment of a heartbeat."
Hulkenberg pointed out that the RP20 has changed since he last drove it at the 70th Anniversary GP meeting in August.
"It felt quite different again to Silverstone obviously, completely different circuit. The car has moved on too, there's a couple of technical bits that are very different and give the driver a very different sensation.
"So I had to kind of adjust around that a bit, and just find my feet again. And obviously, in four laps, that's not so easy. But all-in-all, even though we're last, I'm quite pleased with the laps that we've produced just now.
"It still means that tomorrow is gonna be very difficult, and a hell of a challenge. But we'll do what we can. Obviously I have the experience, the four laps in the pocket now. Those will sink in, and tomorrow we'll just go racing and see what we get."