BULLITT was one of the best car chase films of all time and helped establish the genre when it hit cinemas in 1968.

It also helped launch the Ford Mustang on the road to success and established its street cred.

Now the original car Steve McQueen drove in the movie has been reunited with his grand-daughter, Molly McQueen.

Molly unveiled the 2018 edition of the Bullitt Mustang for Ford at the Detroit Auto Show overnight — after appearing in a short car chase film to tease the audience.

After being driven on stage she got out of the 2018 Bullitt Mustang and stunned the crowd with: “Hi, I’m Molly McQueen and Steve McQueen was my grandfather”.

Speaking about the film which celebrates its 50th anniversary this October, she said: “Now maybe I’m a little bit biased … but it’s crazy you talk to people about great car chase movies and it still remains the gold standard”.

Molly then revealed some secrets that were cut from the movie.

“When I was younger I remember coming across one of the Bullitt scripts in a box in our house. And what really caught my eye … is he’d cross out line after line of his own dialogue,” she said.

“As an actor myself I can tell you that we don’t typically … give ourselves less to say. But he was smart enough and confident enough to strip away everything that was unnecessary, and what was left was thrilling.”

In an era long before product placement — where companies pay big bucks to have their products appear in feature films — Molly said Steve McQueen chose the Mustang for two reasons.

“We all know he loves cars, and truthfully he could have picked any car in the world to be in that movie,” she said.

However, McQueen selected the Mustang for his character Lieutenant Frank Bullitt because: “firstly, it was incredibly important to him to pick a car the average American could afford, especially on a detective’s salary. And second, it’s bad ass”.

The biggest surprise, however, was for Molly.

In the lead-up to this week’s Detroit Auto Show, Ford invited Molly to its design studio on the premise of showing her the new Mustang she would be unveiling.

Instead she was reunited with the original 1968 Mustang her grandfather drove in the film.

The car’s owner Sean Kiernan — who inherited the movie car in 2014 after being in his family since 1974 — introduced himself to Molly with a firm handshake.

“As you know there were two original movie cars,” says Kiernan. “One was recently found in Mexico, that was a stunt car. The other one was actually the one your grandfather drove.”

As they walk over to a car under a cover, Kiernan adds: “Which kind of ties in with my family. When my dad passed away in 2014 I actually worked on the car your grandfather drove in Bullitt”.

By this time Molly starts to twig that she’s not about to see the new Mustang Bullitt.

As the covers come off she says: “No way, that’s so cool!”

Kiernan says the car is in its original condition after filming, and even has the Warner Brothers gate pass on the windscreen, albeit deteriorated.

As he opens the door for Molly to get in the driver’s seat, he says: “There’s been about eight people since your grandfather that’s sat in the car.”

He also pointed out the red tape put on the car’s instruments so Steve McQueen wouldn’t rev the engine too high and kill the V8.

“For two years it was my mum’s daily driver, she was a third grade school teacher,” says Kiernan.

The 1968 Bullitt Mustang was then driven onto Ford’s main stage alongside the new model.

Molly didn’t get to keep the original Bullitt Mustang but she will likely get the keys to the 2018 edition she helped launch.

The 2018 Bullitt is finished in green paint — as with all the Bullitt editions before it — and comes with bigger brakes, a unique exhaust, a cue ball for a gear knob, and Bullitt badging on the boot and steering wheel.

As with the original movie car, the Ford badges have been removed.

Despite the hype — and the fact that the Mustang is Ford’s second biggest selling model locally — the Bullitt Mustang is not confirmed for Australia.

A Ford Australia spokesman said the car is for the US left-hand-drive market only.