It's common for actors to say that making their latest film was a life-altering experience. When Jake Gyllenhaal talks about being profoundly affected by his work on "End of Watch," he's not exaggerating. To prepare for the Los Angeles cop drama, he spent five months cruising crime-ridden neighborhoods in sheriff's department and LAPD squad cars on the 4 p.m. to 4 a.m. shift.

"On my first ride-along in Inglewood, someone was murdered. We were the second car on the scene," he said. "That was definitely a wakeup call. We were involved in stolen vehicle chases. You see domestic violence, disputes that turn violent. You really see your city differently after that."

Gyllenhaal also took on the role of co-producer in David Ayer's film, completing the project for a frugal $7 million. The shooting schedule was a mere 22 days, with ambitious scenes of street violence and chaotic gang shootouts with automatic weapons. With no budget for special effects, Gyllenhall and co-star Michael Peña were peppered by shrapnel from explosive squibs and inside the vehicle during high-speed car crashes.

"A lot of things were done with a split-second to go. We'd only have two chances," he said.

The film opens with a chase filmed by a dashboard camera. "When that windshield blows? We had three of those windshields. If we didn't get that maneuver right and hit the ground running with our guns coming out, we're screwed. We wouldn't have an opening for the movie. It was always dangerous in that way because Dave was trying to make a big, action-filled movie" with scant resources.

In another scene, a tire-screeching pursuit of a drug gang's van ended in a real collision. Peña and Gyllenhaal were tearing down a darkened street when their police cruiser rear-ended the getaway vehicle, a high-impact crash captured on film.

"I put on my producer hat in that moment because I knew we didn't have an extra car." Gyllenhaal's urgent, profanity-laced orders for his partner to get out of the car and continue the chase on foot matched the drama onscreen and remain in the film. "Limited resources and a lot of heart creates something," he said.

The 31-year-old star of "Brokeback Mountain" and "Zodiac" had never played a cop before. In fact, he considered the genre played out. What drew him to "End of Watch" was Ayer's honest portrayal of life on the street. The writer/director (who penned the script for the Denzel Washington Oscar winner "Training Day") grew up in L.A.'s tough neighborhoods and understood the mix of mind-numbing routine and sudden violence that police work entails. "I felt there was a beating heart in this script," and its portrayal of cops as average guys who are called on to display extraordinary heroism.

Gyllenhaal, who lives in New York and made his U.S. stage debut off-Broadway this week, said he sees urban life differently now. "It's hard not to, after having shared [the police officers'] world. There's this weird dichotomy of seeing the world with a little more paranoia, the possibility of something around that corner, and at the same time feeling stronger for it and more confident because of it. Feeling like there is a reality that I now know."

"While that reality's not always the most comforting thing, there's a sense of the truth setting you free, an enlightenment" that has enhanced his devotion to his family, friends and career. "Dave joked when I first met him, 'I'm going to poison your mind. This situation's gonna change you.' And he was right."

Colin Covert • 612-673-7186