The cancellation of the 2021 Bathurst 12 Hour has hurt the amount of GT entries for the Supersprint events on Thursday and Friday, since teams in the endurance classic have used Challenge Bathurst as a test opportunity.

But the lure of Mount Panorama has still proven strong for hundreds of drivers.

Around another 60 entries were received after the closing date on October 22, after organisers removed late entry penalties on interstate competitors, bringing the total to 360 for the four days of action.

Event director James O'Brien said it's been wonderful to see the event going ahead in a strong capacity after it was looking like being a much smaller affair several months ago.

"It was looking unlikely earlier in the year but we determined that unless the event was cancelled on us, as a result of government regulations or restrictions, that we would push on and run the event for as many competitors as we could get, even if they were only from New South Wales," he said.

"Given that almost half the field comes from New South Wales that seemed like a viable option and then obviously with the recent border restrictions easing we've been fortunate enough to pick up competitors from elsewhere."

The fact that teams need to do long term planning for the Bathurst trip means some regular interstate competitors won't be venturing to Mount Panorama this year.

"When entries close weeks out people need to make decisions so [the borders opening] didn't help a great deal but there were some who were already entered in the hopes that those restrictions would be lifted and that proved to be the case," O'Brien said.

"We were a sellout last year but with COVID that was never going to happen this year. Our numbers are around the 360 mark and we had around 430 last year so it's still very healthy."

Numbers at the faster end of town, in the GT3 categories, have taken a hit with the lack of a Bathurst 12 Hour event next year.

Though there's still a great collection of powerful machines ready to take on the Mount this week.

Plus, entries are relatively strong for the regularity category being run on Saturday and Sunday.

"Unfortunately with the recent border announcement in South Australia we lost a few entries [in GT] and with Melbourne opening late we didn't pick up everyone that we normally would, but with that said there are 24 GT cars in that group so it's not a bad result," O'Brien said.

"In regularity we've got 230 competitors out of a capacity of 275 so, given the situation, that's a great result as well.

"A lot of people will have been frustrated this year to not be able to get on a track this year so to get on 'the' track has been quite the lure."