The NYPD unveiled 140 new hybrid vehicles on Thursday, but officials acknowledged significant infrastructure and technology challenges stand in the way of the city’s mandated transition to fully electric patrol cars by 2035.

The new hybrids will help modernize an aging fleet. About 70% of the NYPD's 8,992 vehicles have passed their five-year life cycle. Hybrid vehicles, which typically operate on electricity at lower speeds and gas at higher speeds, make up about half of the NYPD's fleet.

The department currently has fewer than 500 fully electric vehicles, mostly limited to school safety and traffic enforcement duties.

The new SUVs cost about $79,000 each, including the outfitting needed to make them suitable for patrol.

Keith Kerman, deputy commissioner of the Department of Citywide Administrative Services, said the NYPD is ahead of most police departments nationally when it comes to greening its fleet.

"The very fact that the NYPD has established hybrid patrol cars as the standard goes well beyond what most police departments in the country are doing," he said. “And the NYPD is testing plug-in models as well.”

But a lack of adequate charging infrastructure presents the biggest obstacle to fully electrifying the NYPD's fleet. With only 2,400 charging ports for the city government’s 5,700 electric vehicles, Kerman said supporting the NYPD's round-the-clock operations would require massive expansion.

"To get to a place where the NYPD would be able to fast charge immediately, this large of a police force 24 hours a day, that's going to require enormous additional charging," Kerman said.

Finding and testing electric vehicles that can handle the demands of police pursuits is another challenge. Right now there is only one pursuit-rated electric vehicle, the Chevy Blazer, according to Steven Ciregna, executive director of the NYPD's Fleet Services Division.

"They look for acceleration, braking and turning characteristics," he said.

These vehicles face additional electrical demands from emergency lights, dash computers and communication systems that require larger batteries than civilian cars.

The NYPD is testing about 50 pursuit-rated electric Chevy Blazers, according to Kerman, but they're so new they don't yet have NYPD logos.

If the city can find the right cars and build enough charging ports, the department then needs to have backup power systems in place in case of outages or terrorist strikes — a unique concern for police operations.

The new hybrid SUVs announced Thursday will replace older vehicles that have become costly to maintain. The department chose SUVs because Ford no longer manufactures police sedans and officers now carry more equipment.

The purchase includes two Emergency Service Unit trucks and two tow trucks running on renewable diesel made from food oil waste. The hybrids feature a "Police Perimeter Alert" system for ambush prevention and crash avoidance.

The department currently has 3,300 hybrid vehicles in service and plans to purchase 1,000 more soon, making about half of its cars hybrid.

Correction: Due to an editing error, this story has been updated to reflect the correct spelling of Steven Ciregna's last name.