The #3 CoolDrive Mustang was selected to run the new engine earlier this week at Winton when the southern-based teams rolled out given rookie Aaron Love had two days on-track.

Courtney’s #7 Snowy River Caravans car only had the old spec when both BRT entries ran on Thursday but he still had something of a back-to-back comparison, given his entitlement to 10 laps in Car #3 on Love’s rookie day on Wednesday.

“I was fortunate enough to drive Aaron’s yesterday and he had pretty much the whole package on the engine side of things,” the 2010 champion told Speedcafe following Thursday’s testing.

“That was really good, it felt a lot more responsive in those first couple of gears, punching out of the corner.

“So, I think Supercars have done a really good job with all the work they’ve put in, in the off-season, so I think it all looks really quite good at the moment.”

Both the Mustang and Chevrolet Camaro are sporting new aerodynamic packages this season after two rounds of off-season wind tunnel testing in the United States, attended by staff from Supercars’ Motorsport department and the homologation teams.

Dick Johnson Racing’s engine division and Ford, though, continue to work on updates to their Coyote-based 5.4-litre quad cam motor in a bid to improve its moment of inertia after claims last year of a transient disparity relative to the 5.7-litre pushrod ‘LTR’ which powers the Camaros.

The changes have certainly caused a stir in the paddock, and DJR/Ford is understood to have already been instructed to slow their new engine down following Monday’s Queensland Raceway test, where the #11 DJR Mustang also ran with it.

While Ford teams swept the final two events (four races) of the 2023 season after a second in-season aero update which some say may have tipped the parity (im)balance in their favour, Mustangs were blown away in a straight line last October at Mount Panorama.

According to Courtney, who is well-regarded within the industry for his engineering feedback, the new spec is “definitely better than what we had last year.”

He added, “I think, in the off-season, they sort of realised a couple of bits of low-hanging fruit that were pretty easy to knock over and find some performance.

“So, they’ve done a great job with that and I think it’s definitely a lot closer to the mark.

“I obviously haven’t driven a Camaro so I can’t really comment [on if this is the engine package the Ford teams need] – well, not for a long time – but I think it’s a lot closer.”

The 2024 Repco Supercars Championship starts with the Thrifty Bathurst 500 on February 23-25.

READ MORE: Supercars to conduct engine test at Bathurst 12 Hour