Hulkenberg told motorsport-magazin.com: "On better days I can be closer than three tenths to Max.
"Max is a real killer in terms of speed and being his teammate is a difficult task, but it would be interesting to understand where I am in relation to him."
"There aren't that many drivers out there who can do that - just jump in and perform," he told Bild am Sonntag.
"But being a fireman is not what I am striving for. There were teams that wanted me to work permanently as a substitute driver after my first assignment. But a regular cockpit is my priority."
Hulkenberg says Red Bull is clearly "the best option" for 2021, but he acknowledges the chance of securing the seat is small.
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