U.S. Sen. Richard Blumenthal wants to end rollaway car deaths after a woman died in New Canaan.

If a driver cuts their car's ignition but forgets to put it in park, the vehicle can roll away -- sometimes with deadly results. It usually happens with keyless ignition systems.

Kathleen Hofer was killed with her grandson in her arms three years ago when she accidentally left her car in drive. It rolled back and pinned her underneath the vehicle. Her son, Karl Hofer, says her death was entirely preventable.

"When she pressed the button to turn it off, the car was in drive and it rolled backwards and didn't have a safety mechanism to prevent the car from moving," he says.

Norwalk realtor Gabby Thorp died in a similar rollover a few months earlier.

"It's tough,” Thorp’s friend, Susan Hanson, said at the time. “And you keep saying, 'Why? Why did it happen to her?' It makes no sense.”

Now Blumenthal wants prevention systems required in all new cars.

"This kind of technology ought to be standard," Blumenthal says. "These kinds of rollaways are preventable.”

For example, many new Ford cars automatically shift to park when the door is opened or the engine is shut off.

President Joe Biden's new infrastructure bill includes a rollover study. However, Blumenthal says that's not enough.

"I think what they mean when they say 'it's complicated' is, they're afraid of incurring the wrath of the manufacturer," Blumenthal says.

Kathleen Hofer's family is suing Nissan, calling her car "defective and unreasonably dangerous" in a complaint.

In a legal response, Nissan says Hofer’s "negligence” and “carelessness" caused her death, because she was "fail(ing) to operate the vehicle" safely.

Her son says no one should lose a parent like this.

"We think this legislation would really help save lives," Karl Hofer says.

The National Highway Transportation Safety says 142 people died in unattended rollways in 2015, the most recent year available.

In a statement, the agency said: “NHTSA continues to monitor keyless ignition systems, including automatic shutoffs and vehicle rollaway. A number of vehicle manufacturers now include auto shutoff systems in their vehicles, and NHTSA is evaluating those safety features to inform future actions. NHTSA urges vehicle owners to report any potential defect online or by calling 1-888-327-4236."