After putting his new car through a shakedown at Phillip Island last week, he was surprised by the difference the new aerodynamic changes had made.

Changes were applied to both the Mustangs and Commodores in an effort to get better parity across the two marques.

In the Commodore's case, that has resulted in a longer undertray, whilst both cars have some more room to the allowable rear wing angle.

The alterations to the aerodynamics of the Holden Commodore ZB for 2020 have made a 'dramatic' difference according to Reynolds.

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"The car, with the revised aero the car feels a lot different," Reynolds said.

"It feels like we've probably picked up a lot more front and we've got a similar sort of amount of rear as we did last year.

"So the balance shift is quite dramatic for us in the middle of the corner, especially at a high speed corner at Phillip Island."

The governing body of the sport has also introduced a control shock absorber, which means every car will have the exact same shock absorbers.

This used to be where teams could gain a big advantage by having a better shock setup than their rivals, giving better corner speed and reducing lap times.

Reynolds thinks it will help the smaller teams.

"It will actually have a big impact on the sport," he said.

"It's going to make everyone a lot more competitive and it's going to probably take away from some of the bigger teams and add to some of the smaller teams.

"It takes the complexity out of that sort of side of engineering, but it's going to be interesting to see how everyone rolls out at Adelaide.

"Everyone's got the same stuff now - it's not what we had. It's the same for everyone, so there's no massive advantage anymore."

After finishing sixth in last year's title race, Reynolds said he and his team management went through an extensive debrief at the end of the season in an effort to push for a championship in 2020.

"If I had just finished each race where I qualified, I would have finished up second in the championship," he admitted.

"We lost over 650 points during the year with mistakes, this, that and the other, so we had enough car pace to finish second which would have been a huge result.

"So this year is about minimising all those errors and maximising the results that your car can produce."

Heading to round one for 2020 at Adelaide this weekend has its own set of challenges, even though he has done it many times before, Reynolds is respectful of how quickly the fast street circuit can bite, and bite hard.

"It's a difficult track to get your head around and after being out of the cars for so long doesn't help," he said.

"Then you've got turn eight, which is a bastard of a corner.

"You can really turn your weekend upside down if you push too hard early and shunt it, so you have just got to be focused going in and have a clear understanding of what you need to do to make your car better than everyone else's."

The weather is usually very hot and 250-kilometre races on Saturday and Sunday can be a gruelling affair physically for the drivers, over the years a number of them have been unable to finish races due to heat exhaustion.

"I've had one of the best-off seasons in terms of my fitness program, for many years, so I'm feeling really good," Reynolds said.

"I fell out of love with being really fit about four years ago and have only just fallen back in love with it again in the last six months.

"The first race on Saturday is super difficult and funnily enough the Sunday is a lot easier because your body has gotten used to the stress, whereas on Saturday it's a shock to the system.

"But I'm feeling really strong physically and am actually looking forward to that side of it."

The Supercars had their first practice session on Thursday in preparation for Saturday's and Sunday's races.