A General Motors Cruise autonomous test vehicle is parked at a charging station in San Francisco on July 2, 2018. (David Paul Morris/Bloomberg News)

Americans have been shaken by crashes of driverless cars and their semiautonomous counterparts, two recent surveys show, and consumer groups are pushing back against what they say is a flawed effort in Congress to regulate the vehicles.

They have insisted that the Senate put regulatory teeth into a bill they think will be tacked onto a must-pass reauthorization bill to fund the Federal Aviation Administration. A coalition of consumer and safety groups stepped in this week to oppose the bill, suggesting it be sent back to committee to add stricter regulations for the emerging technology.

“We do believe the autonomous vehicle has tremendous potential, but if untested vehicles are let loose into the marketplace, you are going to potentially turn consumers off,” said Jack Gillis, executive director of the Consumer Federation of America, an association of nonprofit consumer organizations. “We are going to slowly turn consumers farther and farther away from the potential of good that the autonomous vehicle can do.”

Two public opinion surveys released this week underscored the growing trepidation over the advent of driverless cars. A Brookings Institution online survey found that 61 percent of Americans said they were not inclined to ride in self-driving cars. A poll done at the weekend by Advocates for Highway and Auto Safety found that 69 percent of those surveyed said they were concerned about sharing the road with autonomous cars.

In addition to the survey responses, concerns over driverless vehicles have echoed in other places: The infrastructure think tank HNTB found in a June poll that 70 percent of people expect autonomous vehicles to arrive within the next 15 years — but 59 percent said they would be no safer than cars with human drivers.

These findings come despite the often-cited figure that 94 percent of car crashes are caused by human error and the fact that most traffic fatalities in 2016 were caused by three factors that fully autonomous cars might eliminate: distracted driving, drunken driving and speeding.

Automakers and technology companies are painfully aware that a crash of a driverless car receives extraordinary media attention, even if the autonomous vehicle is not at fault. When a truck backed into a self-driving bus that was stuck in traffic in Las Vegas in November, a headline said, “Las Vegas’ self-driving bus crashes in first hour of service.”

Companies have been testing vehicles in a dozen states, and one of the industry pioneers — a Google spinoff called Waymo — last week said its test cars were averaging 25,000 miles a day on public roads and had surpassed 8 million total miles since 2009.

Joan Claybrook, who served as head of the National Highway Traffic Safety Administration (NHTSA) under President Jimmy Carter, said this week that overall, “the amount of testing is quite minuscule.”

A spokesman for the Senate Committee on Commerce, Science and Transportation said it remains uncertain whether what is known as the AV START Act will be appended to the FAA reauthorization bill next week.

“Self-driving vehicles are already operating on our roads today — they’re not waiting to see whether or not Congress passes our bill to enhance safety,” said Frederick Hill, a spokesman for Chairman John Thune (R-S.D.).

Hill said the bipartisan bill was “a beginning and not the last word on statutory rules for self-driving vehicles.”

“These critics maneuvering for changes will still have future opportunities to offer their ideas affecting the regulation of self-driving vehicles,” Hill said.

The Commerce Committee approved the bill by a voice vote last year, but it has yet to receive a vote on the Senate floor. That led Thune to consider attaching it to the must-pass FAA reauthorization bill.

It has been held up by a number of Democrats — notable among them Sen. Dianne Feinstein (Calif.) — who want NHTSA to set stricter standards for the industry.

The automakers and tech companies developing driverless cars feared that premature regulatory requirements might inhibit their testing of the vehicles, but Congress felt a need to step in as more test cars populate highways.

The bipartisan bill — heavily amended by both parties — allows NHTSA to grant some manufacturers exemptions from federal safety standards. It also clarifies a fine point born from the fact that traditionally states have licensed drivers and vehicles, while the federal government has been responsible for automotive safety standards and recalls. In a world where there would be no “drivers” of what are called Level 3 to Level 5 vehicles (and where Waymo ultimately wants to dispense with steering wheels and pedals in its Level 5 cars), the bill says federal regulators would govern most aspects of driving.

A Waymo test vehicle with a human at the wheel crashed in Tempe, Ariz., in May when another motorist swerved into it. A second Waymo vehicle that was not in autonomous mode and had an operator controlling it was in a five-car crash in nearby Mesa last month. Police said the crash was caused when a drunk driver ran through a red light and plowed into the Waymo car and other vehicles.

When Tesla’s vehicles in driver-assist mode have crashed, the technology has been confused with fully autonomous cars, creating headlines such as “Tesla driver dies in first fatal autonomous car crash.”

Among the requirements the consumer advocacy groups want added to the bill and stipulated by federal regulations are full disclosure of crashes to NHTSA and the use of event-data recorders like those found in commercial aircraft. They also want requirements for testing of what each vehicle’s computer can “see,” a mandate that makers of fully autonomous cars could not remove steering wheels or brake pedals without federal approval, and permission for states to regulate driverless cars until federal laws are passed to preempt them.

In a conference call with reporters Monday, almost a dozen speakers from consumer and safety groups, universities and law enforcement voiced concerns about the AV START Act.

“Right now, the technology is in the testing phase, and there are far more concerns and questions than there are data-driving conclusions,” said J. Thomas Manger, the chief of police in Montgomery County, Md. “Instead of rushing this to a vote, let’s get if right the first time.”

Ken McLeod, policy director at the League of American Bicyclists, pointed to the death in March of Elaine Herzberg, 49, who was crossing a street in Tempe after dark when an Uber car being tested in autonomous mode with a driver at the wheel struck and killed her.

“Will an AV see me when I cross the road? Will an AV see me if I wear dark clothes?” McLeod asked.

Cathy Chase, president of Advocates for Highway and Auto Safety, said the bill needed “common-sense improvements.”

“The Senate must put the brakes on this bill,” Chase said. “There is no good reason for the Senate to move forward with this bill as currently written.”