It appears that Supercar drivers can wear less safe helmets than required for other minor classes.
https://speedcafe.com/supercars-news-will-brown-liam-lawson-taupo-helmet-swap/
QuoteBrown is embarking on the first of three Toyota Formula Regional Oceania Championship appearances this weekend at Taupo International Motorsport Park.
The driver's first open-wheel outing in six years hit an early snag when his own helmet, which he tested with on Thursday, was deemed an incorrect specification for the class.
Brown subsequently hit the track in Friday morning's opening practice wearing a lid borrowed from Lawson, who is also set to make an appearance at the event this weekend.
https://speedcafe.com/supercars-news-will-brown-liam-lawson-taupo-helmet-swap/