If you drive a car made by General Motors and it has an internet connection, your car’s movements and exact location are being collected and shared anonymously with a data broker.

This practice, disclosed in a letter sent by Sens. Ron Wyden of Oregon and Ed Markey of Massachusetts to the Federal Trade Commission July 26, is yet another way in which automakers are tracking drivers, often without their knowledge.

Previous reporting in The New York Times, which the letter cited, revealed how automakers including GM, Honda and Hyundai collected information about drivers’ behavior, such as how often they slammed on the brakes, accelerated rapidly and exceeded the speed limit. It then was sold to the insurance industry, which used it to help gauge individual drivers’ riskiness.

The two Democratic senators, both known for privacy advocacy, zeroed in on GM, Honda and Hyundai because all three had made deals, the Times reported, with Verisk, an analytics company that sold the data to insurers.

In the letter, the senators urged FTC Chair Lina Khan to investigate how the auto industry collects and shares customers’ data.

One of the surprising findings of an investigation by Wyden’s office was just how little the automakers made from selling driving data. According to the letter, Verisk paid Honda $25,920 over four years for information about 97,000 cars, or 26 cents per car. Hyundai was paid just over $1 million, or 61 cents per car, over six years.

GM would not reveal how much it had been paid, Wyden’s office said. People familiar with GM’s program previously told the Times that driving behavior data had been shared from more than 8 million cars, with the company making an amount in the low millions of dollars from the sale. GM also previously shared data with LexisNexis Risk Solutions.

“Companies should not be selling Americans’ data without their consent, period,” the letter from Wyden and Markey stated. “But it is particularly insulting for automakers that are selling cars for tens of thousands of dollars to then squeeze out a few additional pennies of profit with consumers’ private data.”

Hyundai enrolled any car with an internet connection in the data sharing, the letter said. GM and Honda customers had to opt in to be included, but Wyden called the enrollment process “deceptive.”

The sharing of driver behavior data stopped after the Times reported on it in March. Verisk shut down its data exchange for driving behavior in April.

A spokesperson for Honda, Chris Martin, said Verisk had provided a driving score service to its customers, and that “no identifiable consumer information was shared with any insurance company” without customers’ opt-in.

Hyundai also provided a driving score service. Ira Gabriel, a company spokesperson, said the terms and conditions of its Bluelink connected car service had informed customers that data would be shared with Verisk when they activated Bluelink at the dealership. Verisk shared the data with insurance companies only with a customer’s consent, Gabriel said.

“Verisk paid Hyundai for potential future earnings from customers who affirmatively opted into the insurance feature,” he said in a statement.

Though GM has stopped selling personally identifying information about driver behavior to data brokers, it still shares anonymized location information from its cars with a company that Wyden’s office said GM had declined to identify. According to the letter to the FTC, GM told the office that it did not seek consent from customers to share the location of their cars, and that the only way to opt out “was by disabling the car’s internet connection entirely.”

“As is common business practice, we share de-identified data not associated with specific drivers or vehicles with select partners to enhance city infrastructure and road safety for pedestrians, cyclists and drivers,” a GM spokesperson, Malorie Lucich, said.

Previously, GM shared cars’ locations with a British data broker, Wejo, in which GM had an investment. Wejo filed for bankruptcy last year.

Matt Bialuk, who was an executive at Wejo, said the company had gotten the precise location of about 10 million GM cars up to every one-three seconds, but the data didn’t include identifying details about the driver. The data was useful for colleges and state transportation departments, he said.

“You can see braking, bottlenecks, route optimizations,” Bialuk said. “There are tons of use cases. This is how to create smart roads.”

He added: “We could see windshield wipers are on. Windshield wipers tell a huge story in vehicles.”

This is at least the third letter the FTC has received from Congress asking it to investigate the collection of data from Americans’ cars. In March, the FTC, which is responsible for policing unfair and deceptive business practices, solicited reports from consumers about the issue, but an agency spokesperson said she couldn’t comment on whether the agency is investigating.