"Ambulance" is best when it's content to be gleefully stupid, which is about two-thirds of the time.

It's directed by Michael Bay ("Transformers"), whose explosion-prone testosterone fests are not known for their humor. But surprisingly, most of "Ambulance" plays like a comedy. Jake Gyllenhaal and Yahya Abdul-Mateen II portray Los Angeles brothers Danny and Will, who rob a bank for different reasons: Danny because he's a maniac and Will because his wife needs surgery he can't afford.

The movie gets down to business with the suspenseful robbery and a shoot-out on the streets of downtown L.A. That extended sequence is fairly involving and seems to be an homage to Michael Mann's "Heat" but, since Bay is not the stylist Mann is, comes off more like "Warmth."

At that point, "Ambulance" shifts from "Heat" to "Speed." Danny and Will hijack an ambulance, with an EMT trying to save a gunshot victim in back, and they careen around with hundreds of police cars tailing them. "It's a very expensive car chase right now," one character says, summing up the very movie she's in, and it's an exciting one because it plays out in real time — always a smart choice for a chase film.

All of this is highly unlikely and involves at least two coincidences you won't be able to swallow. But "Ambulance" leans into the silliness, with Gyllenhaal making wisecracks to anyone who'll listen, the cops heckling him, a huge dog along for the chase and the brothers pausing to chill out with Christopher Cross' "Sailing." Dumb? Yes, but I was totally there for it.

Sadly, after the title character has plowed through the piles of pinatas that apparently are heaped on every street corner of East Los Angeles, "Ambulance" goes off the rails. It's as if Bay wants us to pay for the good time we've been having for 90 minutes, so he spends the last 45 straining for significance, making confusing moral distinctions between the characters and — I wish I were kidding — taking a stand for universal health care.

This is not the sort of movie you go to for the acting but Bay has cast it well, with Abdul-Mateen so quietly authoritative that he may never again get a chance to do anything this trashy and Gyllenhaal enjoying his break from the earnest roles he usually plays.

Regarding Gyllenhaal, there's a weird factoid that's bound to show up at pub trivia: After last year's "The Guilty," in which he was a frantic 911 operator trying to get help for a doomed caller, this is Gyllenhaal's second consecutive remake of a real-time Danish thriller in which he walks a moral tightrope.

This latest movie is decent but "The Guilty" comes in at a taut 90 minutes, as opposed to 136 for "Ambulance." So if you plan to see just one Gyllenhaal Danish redo, "Guilty" is the way to go.

'Ambulance'

**1/2 out of 4 stars

Rated: R for language and grisly violence.

Where: Area theaters.