Automakers each would be allowed to test up to 100,000 self-driving cars per year on U.S. roads, and states would be prevented from passing laws to prevent them from doing so under a bill advanced Thursday by a panel in the U.S. House of Representatives.

The measure, unanimously approved by the House Energy and Commerce Committee, would allow the Secretary of Transportation to grant exemptions to federal motor vehicle rules that require cars to have human operators for 25,000 cars per automaker initially if automakers can prove they meet existing safety standards for traditional cars. After a 12-month period, the number of exemptions per manufacturer would increase to 50,000, and it would go up to 100,000 in the third and fourth years.

The current limit for such exemptions to federal auto standards is 2,500 cars for two years at a time. Under the bill approved Thursday, exemptions to federal auto standards would be limited to three years at a time.

The measure was approved after a week of backroom negotiations between Republicans and Democrats on the panel over issues involving the number of test vehicles that would be exempt from federal safety standards requiring a human to be in control of the car and the length of time those exemptions would be good for.

Lawmakers on both sides of the aisle said the compromise legislation represented a rare bipartisan consensus in a typically bitterly-divided Washington.

“It’s bipartisan. This preserves the ability of states to act like they already are,” said U.S. Rep. Debbie Dingell, D-Dearborn, noting that most states do not have the capacity or desire to regulate auto safety instead of focusing on licensing and registration.

Initial drafts of the House self-driving bill would have allowed 100,000 cars per manufacturer each year to be exempt from the existing Federal Motor Vehicle Safety Standard with little reservation. Supporters and critics of self-driving cars have noted that existing U.S. driving rules do not contemplate the development of self-driving cars.

The initial version of the measure also would have increased the number of years that a manufacturer can maintain an exemption from federal motor vehicle standards from two years to five years.

Democrats on the panel had sought to greatly reduce the number of exemptions that would allow automakers to put thousands of self-driving cars on the road in the immediate future, but they said they could live with the compromise that calls for gradually increasing the number over several years.

“I would have preferred no pre-exemptions period, but we were able to narrow it,” U.S. Rep. Frank Pallone, D-N.J., said.

Automakers praised lawmakers for moving the bill to increase the number of self-driving cars that they can test on U.S. roads. The Washington, D.C.-based Association of Global Automakers, which represents foreign-owned manufacturers, said the unanimous vote “is a critical step towards saving lives on America’s roadways.”

Safety groups have complained the exemptions give automakers too much freedom to test self-driving cars on roads with other drivers.

“Pre-empting the states’ ability to fill the gap left by federal inaction on safety standards leaves us at the mercy of manufacturers as they use our public highways as their private laboratories however they wish with no safety protections at all,” John Simpson, Consumer Watchdog Privacy Project Director, said in a statement.

“Lost in the hyperbole over robot cars is a realistic assessment of the likely costs to both consumers and taxpayers particularly over the coming decades, when robot cars and human drivers will share a ‘hybrid highway,’” he added.

The legislation is a big departure from the Obama administration’s proposed self-driving guidelines. They called for automakers and technology companies to voluntarily report information about self-driving testing to the National Highway Traffic Safety Administration before the cars are used by the public.

Under the Obama administration’s proposed rules, which were nonbinding, automakers and technology companies would have had to meet a set of 15 guidelines before they could place self-driving cars on public roads. Automakers complained that such reporting could reveal proprietary information.

The new proposal would require information related to highly automated vehicles to be treated as “confidential business information.”

The new proposed legislation also prohibits states and other local jurisdictions from adopting regulations related to cars’ design, construction, software or communication. States still would be allowed to regulate registration, licensing, liability, education and training, insurance or traffic laws. The Obama-era recommendations just offered guidelines that suggested states allow federal regulators to take the lead on crafting self-driving rules

Michigan had already taken steps to position itself as a haven for self-driving car testing: The state Legislature passed into law last year a measure that allows robotic cars to be operated on any Michigan road without a driver behind the wheel. Backers of the technology in the state have said they are not concerned that a law setting uniform standards across state lines would have a chilling effect on Michigan’s efforts.

Supporters of the measure moving now in Congress anticipate a full vote of the House will come in the fall.

Lawmakers in the U.S. Senate have said they also are working on a bipartisan bill to regulate self-driving cars. They have released a set of principles that call for prioritizing safety, promoting innovation and strengthening cybersecurity, but have not agreed on specific language.