The California Air Resources Board’s modification of its tough zero-emissions mandate, allowing some automakers to try and reach their prescribed manufacturing targets with hybrid-electric vehicles instead of zero-emissions vehicles only, leaves the companies hopeful the typically unrelenting regulatory panel may be open to further changes.

“Volvo Cars is satisfied with most of CARB’s recent decisions, though we are still working together to find a win-win scenario for compliance credit requirements,” Katherine Yehl, director-government affairs for Volvo Cars, tells WardsAuto by email.

Alex Fedorak, a spokesman for Mitsubishi Motors North America, says his company “supports the intent of the ZEV mandate – increased sales of plug-in electric vehicles. We believe the most recent decision is a good step forward.”

However, straying from CARB’s exclusive emphasis on EV technologies, he adds, Mitsubishi is pursuing “highly efficient internal-combustion engines” in addition to EVs and PHEV technologies.

“This is a global effort and requires all stakeholders to work together to transform the on-road vehicle fleet to meet the challenges of fuel conservation and greenhouse gas reduction,” Fedorak says, “specifically, the development of alternative-fuel refueling infrastructure and market development.”

Volvo and Mitsubishi, along with Mazda, Jaguar Land Rover and Subaru, comprise the group of intermediate-volume manufacturers that, due to their limited resources in relation to bigger automakers, have asked to be exempt from the zero-emissions production requirements. Each of the five automakers pulls in less than $40 billion in revenues annually.

The regulatory agency opted instead to give the so-called IVM5 both an added hybrid option and a later compliance date of Jan. 1, 2018, by which time each company will be expected to have an approved pure ZEV or hybrid transitional ZEV (TZEV) on the market.

In the state’s complicated way of determining ZEV credits, though, the TZEVs would earn fewer credits than pure ZEVs. If an automaker’s sales of TZEVs fell short of the amount of credits demanded by CARB, however, it could buy those credits from another party.

Tesla has emerged as a likely merchant in such transactions, as its EV-only operation has amassed a stockpile of extra ZEV credits over the years. Other automakers such as General Motors and Toyota also have credits to spare.

David Clegern, public information officer for CARB, tells WardsAuto in a phone interview that TZEVs, which are not considered full hybrids, are counted as ZEVs “under our regulations because for most local driving, which is the majority of trips taken, they do not run on fossil fuel.”

Because TZEVs earn fewer credits than BEVs and hydrogen fuel-cell vehicles, he continues, the intermediate manufacturers, who “generally do not have the model line to permit them to develop a plug-in and BEV or FCEV simultaneously...will have to deliver more cars than the large manufacturers, because they have the same credit requirements.

“California will reach its ZEV targets.”

The minimum ZEV production requirement has been boosted over time, as CARB seeks to meet the state’s goal of 1.5 million ZEVs on roads by 2025.