California is adopting rules that would mandate that nearly every trip through Uber’s or Lyft’s platforms would need to be in electric vehicles by 2030.

The rules, adopted by the California Air Resources Board this week, say that electric vehicles, EVs, should account for 90% of all ride-hailing vehicle miles traveled in the state by 2030.

This is actually a lesser goal than the two app-based ride-hailing companies have set for themselves. Both Uber and Lyft have committed to converting their U.S. fleets entirely to EVs by the next decade, according to Reuters.

However, the companies admit even their own goals are unrealistic without additional subsidies for EVs and a more robust charging infrastructure.

Board members in discussing the measure also expressed concern that there was no way for the agency to make sure the companies bear the costs, and not the drivers.

Uber had previously announced it would invest $800 million in the next few years to help its drivers switch to EVs.

The state’s regulation can also be met by reducing so-called “deadhead miles,” miles driven without a passenger, or by increasing the number of passengers per trip, the agency said.