If you want to impress, one of the surest cheats for predicting best picture at the Oscars has always been scanning the Producers Guild Awards.

With a huge overlap in eligible voters, the PGA’s top gong almost always matches the eventual Oscar champ.

Granted that went haywire in 2017, with PGA voters plumping for La La Land instead of Moonlight (as did the envelope-bearers, whoops!) and The Big Short instead of Spotlight in 2016, but most times you’ll be fine.

So when director Peter Farrelly’s Green Book added PGA triumph to its Golden Globe for best motion picture (musical or comedy), it technically secured front-runner status even before the Oscar noms announcement earlier this week.

So why has award-grabbing Green Book – which has also seen star Mahershala Ali win a Golden Globe and Viggo Mortensen nominated repeatedly – received significant popular and critical pushback?

A reverse Driving Miss Daisy named after a publication listing safe hotels in the segregated southern states of the USA, it is inspired, perhaps too loosely, by the real life story of African-American classical/jazz pianist and closeted gay man Dr. Don Shirley (Ali) enlisting the aid of Italian-American bouncer Tony ‘The Lip’ Vallelonga (Mortensen) to chauffeur him to gigs throughout these fraught states.

Farrelly, better known for broad comedies like Dumb and Dumber and There’s Something About Mary, co-wrote it with Brian Currie and Tony’s real-life son, Nick.

Firmly played for feel-good laughs, it feels far too fluffy in a best picture field also including BlacKkKlansman and even Marvel’s Black Panther.

Simplistically exploring the racial politics and barely touching the sexual ones, it frustratingly centres Tony’s woke-awakening over Don’s impossible position.

As NBC’s Jenni Miller put it, it’s a movie about racism made by white people for white people, adding, “Unfortunately for Mortensen, his character isn’t really salvageable, and Lip as written leaves a Fonzie-like aftertaste in your mouth.”

While there are plenty of positive reviews, with a fresh Rotten Tomatoes score of 81 per cent, most note the performances overcome the treacle and dodgy whiff of white saviour.

Others are more brutal. The New York Times critic AO Scott warned, “There’s not much here you haven’t seen before, and very little that can’t be described as crude, obvious and borderline offensive, even as it tries to be uplifting and affirmative.”

The AV Club’s AA Dowd described it as a “comforting liberal fantasy, a #NotAllRacists trifle that suggests that our deep, festering divisions can be sutured through some quality time on the open road, resolving differences over a bucket of KFC.”

One Twitter user suggested, “Green Book is like if someone watched Hidden Figures and thought we need a movie on the Kirsten Dunst character.”

But the movie has had to overcome more than divisive reviews to take the lead during awards season.

Oscar nominee Mortensen profusely apologised for using the N-word in context, but ill-advisedly, during a Toronto International Film Festival Q&A.

Mortensen was “worried about doing a caricature” in Green Book. Photo: Universal Pictures

Then writer Vallelonga deleted his Twitter account after an old Islamophobic tweet resurfaced, supporting then-Republican nominee Donald Trump’s false claim that Muslim men in New Jersey cheered as the World Trade Centre fell in 2001.

When an old interview of Farrelly showed up, revealing that he used to enjoy flashing colleagues for laughs, it did not go over well in the ‘Me Too’  era.

Throw in the fact that Shirley’s family has criticised the accuracy of events depicted within the movie, and you have a lot of muck.

While none of it seems to have stuck, we’ll know for sure if Green Book falls at the final hurdle in favour of The Favourite or Roma, or is a shock upstart, when the Oscars broadcast live in Australia on February 25.