Regulation loopholes and a lack of post-crash probes have conspired to make stretch limousines some of the most dangerous rides on the road, Sen. Chuck Schumer said Sunday in demanding greater oversight after last week’s nightmarish Schoharie smash-up that killed 20 people.

“For every inch the limousine stretches, they get considerably more dangerous,” Schumer said in a press briefing at his Midtown office.

Part of the issue, Schumer said, is the regulatory “gray area” that the party vehicles fall into.

“They’re not a car, [and] they’re not a bus,” said Schumer. “They fall through the regulatory cracks, and there are no safety standards for them. That has to change.”

While limousines are regulated, stretch limos are modified with less supervision aftermarket, and aren’t required by federal law to have such safety features as passenger seatbelts and overhead airbags, Schumer said.

Compounding the issue is that when stretch limousines do crash — 12 such collisions caused a dozen deaths between 2012 and 2016, according to the National Highway Traffic Safety Administration — the feds are often the last ones to know, Schumer said.

“I’ve spoken to the chairman of the [National Transportation Safety Board] and he says, ‘We don’t know when a limo crashes,’” Schumer revealed. “So I’m going to ask state authorities throughout the country to notify the NTSB when there is a stretch limo crash, so they can go investigate.”

Schumer said that that lack of formal studies of the accidents leaves officials wanting for safety recommendations to make them less prevalent and deadly.

The NTSB is only probing the Schoharie accident, in part, because Schumer asked them to investigate collisions involving the vehicles after a horrific July 2015 crash that killed four women on a tour of Long Island’s vineyards, the senator said.

But the carnage of that crash pales in comparison to the hellish Schoharie collision, which left 20 people dead: 17 passengers on their way to a birthday party, the underqualified driver, and two pedestrians.

“We all are grieving for the terrible crash that occurred in Schoharie County,” he said. “We want to avoid this from happening again.”