Even with a botched perm, Matt Damon shows true grit as Carroll Shelby in 'Ford v Ferrari'

LOS ANGELES – Matt Damon was willing to do whatever it took to play fearless racing legend Carroll Shelby in "Ford v Ferrari."

If that meant having to undergo the first perm of his life to re-create Shelby's naturally curly hair, Damon was going to do it. Even if it led to his first perm emergency.

"They just fry your hair. And then my hair kind of went a shade of red," Damon says at the Four Seasons Hotel, his hair restored to its supreme straightness. "So I had a little perm emergency. That’s where the hair dye came in."

A pit crew on the set brought his locks back to Shelby's darker color, though the look isn't a perfect match. That's OK with Damon: The 5-foot-10 star knew he was never going to physically resemble the 6-foot-3 Shelby in the movie (now in theaters).

Read our review:  The bromance is real in Matt Damon and Christian Bale's retro cool 'Ford v Ferrari'

He could capture the spirit of the man who teamed with driver and engineer Ken Miles (Christian Bale) to design the ultimate race car for Ford Motor, a machine that could beat even Ferrari in the unforgiving 24-hour Le Mans race. 

"I cannot grow for the part. There are limits to what I could do,"  Damon says. "I don’t look anything like him, and I’m very different from him personality-wise."

It's one heck of a ride watching Damon and Bale team up in the real-life underdog story – with enough heart in the tank to win over movie fans who don't know the difference between Le Mans and Lamaze (the method of childbirth).

"I wanted to show the private side of Carroll Shelby. That’s where I really connected to him, somebody who wanted to collaborate with other people that he loved and respected to build something bigger than him," Damon says. "For Carroll Shelby, that was cars; for me, it’s movies. So in that deep level, I really understood him."

Director James Mangold says he was intrigued to see Damon's chemistry with Bale in the first film pairing of two major Hollywood luminaries. He knew Damon wouldn't overplay the larger-than-life Texas persona of Carroll, who died in 2012.

"Someone could almost take this role too far and turn it into Foghorn Leghorn," Mangold says. "I thought Matt would go a little easier on the barbecue sauce."

For Damon, slipping back into the Texas accent was as easy as pie, using the same dialect coach he worked with on films such as the Coen Brothers' 2010 Western "True Grit" and 2000's "All the Pretty Horses."

Working with Bale was a "dream," Damon says, praising the Oscar winner's multilayered portrayal of the hot-tempered Miles. The only flare-up on the set came as the two battled hilariously onscreen in a middle-aged man fight that involved the "Bourne" action star slapping "Dark Knight" Bale repeatedly on the head with a loaf of Wonder Bread as cans of Campbell's Soup spill out of a grocery bag.

"That Wonder Bread was definitely injured," Damon says. "We’ve spent so many times in our career in rooms with mattresses on the floor and stunt teams trying to make us look like we know what we’re doing. This was the opposite. We had to look like what we are, these middle-aged guys who tired out pretty quickly, and show the silliness of it."

The fight was so ridiculous that even when Bale grabbed a garbage can lid to fend off Damon's advances, the first concern was about safety.

"I tried to punch him as he holds up the trash lid, and I hurt my hand. And Christian stops and says, 'Are you OK?' That was the spirit of the fight," Damon says.

The sometime action star was able to tap into his inner Jason Bourne in the instantly classic scene in which Carroll takes Ford's imperious CEO Henry Ford II (Tracy Letts) out on the racetrack to test one of the fastest race cars ever produced: the Ford GT40 MK II. 

Knowing that he'd need to appear as if traveling well over 100 mph was his day job, Damon asked stunt coordinator Rob Nagle to take him out for a hair-raising pre-shoot spin.

"I had to get all of that stuff out," Damon says. "You feel giddy when you do it the first time. So after that, I was able to look like this is no big deal."

Damon looked cool at the wheel (while Nagle actually drove from a compartment perched above the car) as it hit high speeds and ended in a 720-degree turn that prompted Letts' Ford II to collapse into tears, then uncontrollable laughter.

"We called action and peeled out, and you see us flying around," Damon says. "So that's really what is happening. The rest was 100% Tracy Letts."

Damon is moving at high speeds on another dream project, a new screenwriting collaboration with Ben Affleck and Nicole Holofcener, his first with Affleck since "Good Will Hunting" brought the struggling Boston actors instant fame and best screenplay Oscars in 1998. "The Last Duel" focuses on the final sanctioned medieval duel between two knights, over a claim that one had raped the other's wife.  

The project continued even when Affleck returned to rehab for alcoholism last fall, though he'll no longer star as one of the knights as planned (Affleck takes a smaller role). "The Last Duel" is being fast-tracked with Ridley Scott directing.

"Ben and I and Nicole wrote really fast and gave Ridley like 60 pages. He stopped everything and said, 'This is the next movie I’m doing,' " Damon says. "Suddenly, we had a deadline."

Damon knows there will be high expectations for the movie by the best-friend superstars, especially since, he jokes, "we’re batting 1,000, we’re one-for-one together."

But he's focused now on "Ford v Ferrari," which moves into awards season with critical acclaim. Damon's first order of business after capturing Shelby onscreen was cutting off his perm.

"There were thoughts on the hair at home, but these were never thoughts of keeping it," Damon says. "The minute I got clearance, the footage is all good, there’s no chance for reshooting, that 2 inches of (curled) hair was gone. I had it chopped."