"I’ve been fortunate over the years with teams I’ve raced with that they’ve put me in a position to get good results in good cars," he said.
"Any next move, I want to do the best thing for my career and my family.
"The focus, first and foremost, is giving myself the best chance I can to win Bathurst.”
Less than two weeks later, Coulthard has been confirmed with WAU, returning the 471-race start veteran to the Walkinshaw fold.
The New Zealander raced out of the Walkinshaw stable on a full-time basis in 2010 and 2011.
He raced for Brad Jones Racing between 2012 and 2015, before shifting to DJR Team Penske.
Coulthard won 13 races between 2013 and 2020, and finished third in the 2017 Great Race.
Coulthard left Team Sydney earlier this year
Luff joined WAU in 2014; he won the 2015 Enduro Cup and 2016 Sandown 500, and scored four Bathurst podiums.
He finished fifth with Bryce Fullwood last year.
"We are absolutely rapt to have two drivers of Fabian and Warren’s calibre with us for Bathurst this year, it puts us in a really strong position alongside Nick and Chaz,” WAU team boss Bruce Stewart said.
"Fabian was a clear target of ours once he became available. There’s no doubt he has the talent to be a full-time driver in the category, so to have him with us is fantastic, and really strengthens our line up that’s for sure.
"Luffy joins us for year nine now, and we couldn’t speak more highly of him and what he’s done for our team. You just know he is going to do an excellent job every time he gets in the car.
"I’m really excited to see how all four drivers go this year, we’ve got a really important test day today to kickstart our year, so it will be great to have Chaz, Nick, Fabian and Luffy all get behind the wheel."