Most observers felt that Brock adapted to the powerful Sierra's quicker than most, though he readily admitted his link with Rouse and the technical help he gave was a big factor in the Mobil teams revival.
The two B&H cars had been acquired from the Wolf Racing Australasia team formerly run by Robbie Francevic and his long-time patron Mark Petch.
The M3 was reduced to a class runner and it was left to privateers John Cotter and his regular co-driver Peter Doulman running one of the ex-JPS/Mobil M3's purchased from Brock at the end of 1988 to keep a BMW presence on the grid.
Skaife made his first appearance of the series at the Mallala circuit in South Australia for Round 5, and avoided the first corner carnage (caused by an out of control Brock) to finish a fine fifth.
The Holden Special Vehicles team did not compete in the series, despite entering two Commodores for highly respected British driver Win Percy and Channel 7 commentator Neil Crompton in the opening round at Amaroo Park (a fact that Crompton's co-commentators Mike Raymond and Gary Wilkinson constantly reminded him about during the race telecasts).
Allan Grice was the highest placed Holden driver in the championship, finishing in a hard-fought fourth position after a one-off appearance at Winton in a privately entered Roadways Racing Commodore he had driven in the 1988 Tooheys 1000.
It was Holden's lack of representation from the factory backed team or the privateers that highlighted the growing costs of Group A racing, something which would cause a change in the sport after 1992.
Mallala returned to the championship for the first time since 1971, replacing the round at the Bob Jane owned Adelaide International Raceway.
Dick Johnson went on to win on his home circuit for the first time since his epic battle with Brock which won him his first ATCC back in 1981.
1989 would prove to be the last ATCC contested by four-time champion Allan Moffat with the Canadian born driver retiring from driving at the end of the year.