Some of the most vocal objectors to the $1.6 billion settlement with Toyota Motor Corp. have agreed to drop their challenge in exchange for $1.5 million to research electronics systems used in cars.

Two objectors to the settlement—backed by the Center for Auto Safety, a Washington nonprofit founded by consumer advocate Ralph Nader, and the Consumers Union—had argued that a $30 million auto safety research fund established by the settlement essentially endorsed Toyota’s position that drivers, and not defects in the electronic throttle control system of their vehicles, were to blame for accidents. That dispute lay at the heart of the litigation.

After U.S. District Judge James Selna approved the deal on July 24, 2013, rejecting those arguments, Maryland residents Allen Snyder and Linton Weeks filed a petition with the U.S. Court of Appeals for the Ninth Circuit. Clarence Ditlow, executive director of the Center for Auto Safety, filed a declaration supporting the objectors.

Last month, the organization and the objectors reached an agreement with members of the plaintiffs steering committee in the underlying case. According to a court notice filed on Tuesday, the agreement requires that the five lead plaintiffs firms in the sudden-acceleration litigation forfeit $1.5 million from their attorney fees to finance research into automotive electronics.

Sharing the money would be the Center for Advanced Life Cycle Engineering at the University of Maryland and the Automotive Safety Research Institute, a nonprofit organization in Charlottesville, Va., headed by Kennerly Digges, director of biomechanics and automotive safety research at the National Crash Analysis Center at George Washington University, which operates in conjunction with the Federal Highway Administration and National Highway Traffic Safety Administration.

The plaintiffs firms are Seattle’s Hagens Berman Sobol Shapiro; Cotchett, Pitre & McCarthy in Burlingame, Calif.; Houston’s Susman Godfrey; Robinson Calcagnie Robinson Shapiro Davis in Newport Beach, Calif.; and San Francisco’s Lieff Cabraser Heimann & Bernstein.

“Clarence Ditlow and others brought up some very important issues regarding the need for safety research as part of the Toyota settlement,” Steve Berman, managing partner of Hagens Berman, said in a prepared statement. “This was the last remaining issue that awaited resolution before funds could be distributed to former and current Toyota owners and lessees.”

Ditlow and Mark Chavez of Chavez & Gertler in Mill Valley, Calif., who represents Snyder and Weeks, did not respond to requests for comment.

The underlying settlement would resolve claims by consumers that their cars lost value following the highly publicized recall of about 10 million vehicles due to defective floor mats and gas pedals.

Toyota has formulated a proposal to resolve another 450 sudden-acceleration cases, brought on behalf of passengers and drivers who were injured or died in accidents blamed on sudden acceleration. Selna has scheduled a Jan. 14 hearing on the proposed process. Official responses to the proposal were due on Wednesday.

Contact Amanda Bronstad at abronstad@alm.com.