Mayor de Blasio says all New Yorkers must change their lifestyle to curb carbon emissions — well, all except one man: Mayor de Blasio.

Hizzoner portrayed himself as an eco champion on Friday, announcing plans to ban plastic bags and beef up enforcement against idling vehicles, and called on all his constituents to alter their habits in light of President Trump’s withdrawal the Paris climate accord.

“Everyone in our own life needs to change our habits to start protecting the Earth,” he said in his weekly appearance on WNYC radio.

But when asked to explain why he needs a motorcade of gas-guzzling SUVs to take him from Gracie Mansion to Park Slope, Brooklyn, just to exercise at a YMCA, he didn’t have an answer — and declined to give up the habit.

“The issue is not cheap symbolism,” he said testily.

The question was raised by a caller into the show.

“How about you stepping up your game and leading by example [by] getting out of your SUV armada?” said the caller, Charles Komanoff, a longtime energy-policy expert from Manhattan and a Carbon Tax Center founder.

“And if you need to go to the Park Slope Y five days a week rather than a gym near you, why don’t you take mass transit or even once in a while ride a bike like the vast majority of your fellow New Yorkers so you will know how we are suffering under a transit system?”

De Blasio defended his rides by noting that his SUV is a “fuel-efficient” hybrid.

“I wish my life was like everyone else’s, but it’s not, for obvious reasons. But again, the issue is not cheap symbolism here. The issue is, Are we going to take action? Are we going to change the way things are done?” he said.

The mayor is ferried to the Y by two SUVs — a regular GMC Yukon XL, which burns 16 mpg in the city, and a Chevrolet Tahoe Hybrid, which is only slightly more fuel efficient at 20 mpg.

De Blasio also suggested the city would start cracking down on idling cars — even though his own fleet has been caught waiting with their engines on for up to an hour outside the gym.

“Idling is a huge problem, and blocking the box is huge problem,” the mayor said. “I will have more to say on that in the coming weeks.”

Komanoff, who said he voted for de Blasio in the last election, later told The Post he was “appalled” by the mayor’s “tone deaf” reply to his question.

“This whole ‘tale of two cities’ thing — I guess he really fancies himself as one of the little guys,” he said, invoking de Blasio’s campaign theme. “Most of us are little guys, and no one looks on him as one of us when he gets ferried everywhere in his armada.”

He said the mayor’s fuel-burning trips to the gym set a bad example.

“This is what makes the climate issue such an easy mark for the right wing,” he said. “It’s so easy to characterize this [as an issue] the elites drag out to make the common person feel bad for driving around in a pickup truck.”