Calling time last year on a four-decade career in the automotive industry – leaving his role at the top of Toyota Australia as it completed the transition from manufacturer to full-line importer – Buttner expected, proverbially, to retire to a quiet life on the farm.
"After 41 years in this industry – suffice it to say, I have a fantastic passion for this industry – and being very honest and transparent, on the 31st of December last year I retired. I've spent time with my wife of 41 years – more time than I have in those 41 years – and good time with the grandkids," he says.
Despite growing up a Holden boy, Buttner kicked off his career with Ford, working in various roles from 1976 to 1987.
It was then that he moved to Toyota and worked up through manufacturing to build a relationship with the dealer group that helped drive the Japanese giant to number one in the Australian market.
His appointment as successor to former Chairman and Managing Director Mark Bernhard is clearly a coup for the local General Motors operation, as it works to arrest sliding sales in the Australian market.
"With Mark announcing his retirement, that afforded this opportunity," Buttner told assembled press at an informal meet-and-greet this week, wisely hosted not at headquarters or an upmarket restaurant, but at a Holden dealership in Melbourne.
Buttner is widely regarded as 'one of the good guys' in the Australian industry, but he's a sharp operator. Coming out of retirement for this gig, he says, meant he needed to be doubly sure it was the right place and time.
"I didn't jump at it lightly or quickly, and I wanted to understand a bit about this iconic brand that I grew up with in a family, a Holden family growing up in Bendigo, and I can still remember the number plates of the Holdens that my dad had over the years.
"So there was this innate passion for the brand inside me, and then when I started speaking to GM International, naturally one of the first questions on my mind – which I know is on a lot of people's minds – is, well, what's the future source of product, what's your commitment to Holden and Australia?
"And, frankly, I was buoyed by their responses, to the extent that it made me investigate further. I thought, well, if I'm going to go to a brand, I've got to have belief in the product. To stand in front of people like yourselves (the press), and say I've driven the product, it's good product, it's meeting the needs of the marketplace.
Buttner says he did just that, before accepting the job. He had Holden bring its cars out to his farm, spending a couple of weeks in them and having his wife drive a few, before deciding he could trust in the product he'd be selling.
"I was really impressed with the product," he says. "And the work being done by the product engineers here in Australia to tune the ride and handling impressed me."
But what about the brand's culture? This is a newly reduced and restructured group working to sell product that isn't entirely resonating with the market and – in the case of the European-imported Commodore and Astra – will need to be replaced by some other unknown GM product down the road.
Buttner assures us (it's his job to be convincing here, and he is), there's a spirit at Holden not so easily defeated.
"I asked the specific question of HR: what's the employee satisfaction like? Again, I was buoyed by their positivity and their strong connection to the brand. To a person, there's deep desire to ensure the brand is successful and lives up to the expectations of the consumer."
That's at headquarters. What about the dealer body? It's no secret, Holden dealers are less than rapt with the sharp decline in sales, no longer living anywhere near the top of the sales charts.
A large part of Buttner's success at Toyota was founded on his work with dealers, and he'll be pouring that experience into his new job with Holden.
All the same, the new Holden boss believes working closely with the dealer group will be key to turning things around.
"I honestly believe, I think you know me well enough, I believe collaboration is the most important thing we have. So, we as a factory can have the dreams and targets we want, but there's a whole host of stakeholders that will determine our success," Buttner says.
"We try and drive the foot traffic and the enquiries into dealerships around Australia, so the stronger our partnership can be with the Holden dealer network, and the stronger they can see our commitment and from GM International, then I think the more buoyed they'll be to really drive hard to sell more cars.
"Over time, we have to ensure we grow our volume and share. We have to be profitable; everybody wants a return on investment and dealers are no different. GM's no different, we're no different at Holden," he says.
Don't call him Mr Fix-it, though. "I don't think I'd call myself that at all. I'm a person who has a great passion for the brand. I've been employed to come in and sell more volume, and make sure that all the stakeholders are engaged, so we can grow volume and share down the track.
Buttner is the eighth new Holden boss in 13 years, and although he's been pulled from retirement for this job, he expects to stick with it for a while.
"I certainly hope so mate, I'm only a spring chicken!"