A driver rides hands-free in a Tesla Model S equipped with Autopilot hardware and software in New York on Sept. 19. California says a true autonomous vehicle is one that is “equipped with technology that has the capability of operating or driving the vehicle without the active physical control or monitoring of a natural person.” (Christopher Goodney/Bloomberg News)

California regulators have proposed banning the word “autopilot” from electric-car pioneer Tesla’s advertising, teeing up an extraordinary conflict between state officials and the Silicon Valley powerhouse in an era of increasingly automated cars.

The move, in draft state regulations on autonomous cars released late Friday, marks an affront to Tesla’s ambitions and self-image. And it represents a muscular exertion of state power as state and federal officials are working through how they should govern vehicles that soon may require no human driver at all. Some of the state proposals are in line with the wishes of manufacturers; others, far from it.

“Autopilot” is the name for a set of semiautonomous Tesla features that fall far short of the driverless future that tech titans and U.S. officials have embraced as a business and safety opportunity. The company, led by Elon Musk, has argued that the sensors and software that enable those capabilities are part of a fast-evolving system that, working with today’s drivers, has already crossed the “ ‘better-than-human’ threshold.”

But the California Department of Motor Vehicles cited concerns about “the risk of driver complacency and misuse of lower level systems where drivers are expected to remain fully engaged in the driving task.” It said drivers must be aware of the limitations.

“The terms ‘self-driving,’ ‘automated,’ ‘auto-pilot,’ and other statements that lead a reasonable person to believe a vehicle is autonomous constitute advertising regulated by the truth-in-advertising provisions in the Vehicle Code,” the state said. A true autonomous vehicle that could use such terms, California says, is one that is “equipped with technology that has the capability of operating or driving the vehicle without the active physical control or monitoring of a natural person.”

Other car companies would also be affected. Mercedes-Benz, for example, was criticized for an ad that suggests one of its cars “can drive itself,” though it too had only limited automated capabilities.

Tesla defended its word choice.

“Autopilot makes driving safer and less stressful, and we have always been clear that it does not make a car autonomous any more than its namesake makes an aircraft autonomous,” a Tesla spokeswoman said.

A deadly May crash of a Tesla on Autopilot in Florida is under investigation by the National Highway Traffic Safety Administration. Musk said last month that a software breakthrough improving Tesla’s radar technology will make his company’s cars, which he said are already the safest on the road, much safer still. The new software has since been downloaded remotely to Teslas around the world and probably would have prevented the May crash, Musk said.

California’s newly released draft regulations are a mixed bag for tech firms and carmakers more broadly.

They, for the first time, set out state rules for deploying driverless cars with no humans on board ready to take over. Many top companies promoting driverless technology, including Google and Uber, are based in California and had been pushing hard for that.

At the same time, California proposed that manufacturers “must obtain an ordinance or resolution from local authorities” laying out circumstances under which the cars can be tested on local streets. That raises the specter of a whole new layer of government involvement, and with it the potential for messy and prolonged community struggles.

In contrast, the Michigan Senate last month prohibited local governments from imposing any “fee, registration, franchise, or regulation on an on-demand automated motor vehicle network,” such as those proposed by Ford and GM, through the end of 2022. That was intended to prevent a patchwork of local community standards that could stymie driverless development.

Uber is already pursuing a modest version of such a network in Pittsburgh, with some users of its app eligible to ride in driverless test cars with chaperons at the wheel.

Google, which has operated several generations of autonomous cars around its headquarters in Mountain View for years, declined to comment on California’s proposed rules.

Tesla is pushing to make its cars fully autonomous, and also available to essentially be rented out by a network of owners to reduce individual costs. The company declined to address questions about California’s proposals overall.

“Tesla is reviewing the draft regulations and will provide input to the DMV as appropriate,” the company said in a statement.

Its previous input has sometimes come in cutting terms barely camouflaged in bureaucratic niceties. Fully autonomous cars will save many lives, the company says.

“The Company does not ask if this technology will ultimately be safer than humans, but rather when will it reach that point,” Matthew Schwall, the company’s director of field performance, wrote to federal safety regulators in May. Once that happens, if “restrictive regulation” or “cumbersome certification procedures” stymie the technology’s rollout, that will be a “disservice to consumer safety.”

“Put more simply, if the regulatory environment impedes the development, deployment, or adoption of a safer driving alternative to humans, then it will contribute to vehicle fatalities that otherwise would have been avoidable,” Schwall wrote.

Last month, the Obama administration released federal guidance that was bullish on the projected safety benefits of self-driving cars. It outlines a 15-point safety assessment for companies to follow. It also sought to keep federal control over vehicle safety regulations, including for driverless cars, saying there should not be 50 individual state safety standards. States should focus instead on more traditional functions such as licensing drivers, the federal guidance said.

California embraced the idea of the 15-point assessment and said it had worked closely with federal regulators as it shaped its guidelines. What balance California ultimately strikes on the proper state role will depend on reaction to the draft regulations, including in upcoming public comment sessions, before officials push ahead with formal rules. The state DMV did not immediately answer questions on the possible impacts of the proposals.

In his May letter, Schwall made clear Tesla’s concerns about the potential for overreach. If states are allowed to slow the widespread adoption of automated vehicles, he said, their actions “will ultimately result in decades of additional annual vehicle fatalities that otherwise would have been avoidable.”