Should he add a second Supercars title to his long list of achievements in 2021, van Gisbergen knows his team needs to step up with its cars.
"We had a lot of test items, but the main thing was reliability," he told Chad Neylon reporting for Supercars.com.
"We had a couple of issues last year. So, just logging a lot of laps, Garth had a few race runs too.
"It was good. Car was faultless all day, and we had the most laps by a fair bit."
The 31-year-old enjoyed a productive summer in his native New Zealand after he returned home following his Bathurst triumph.
Notably, he won the iconic New Zealand Grand Prix in a Toyota open-wheeler, won the Battle of Jacks Ridge rally event in a Team Ralliart Mitsubishi, and steered a Ford Escort RS1800 in the City of Auckland Rally.
He also steered Triple Eight's Mercedes GT car, but said he felt most at home behind the wheel of the Red Bull Ampol Racing Commodore.
"It's awesome for the guys," he said, regarding a clean test day for his team.
"No issues all day… I’ve been here all week in a GT car, I'm learning to drive properly again and not be lazy with the pedals.
"It's awesome to drive a V8 again. Straight away full throttle, feeling the power.
"I drove a lot of cool stuff over the summer, but this is just a proper, pure race car."