The Association for Renewable Energy & Clean Technology (REA) has called for a new CO2 cap, with vehicles producing above a certain threshold not allowed.
It said a meaningful ZEV mandate should ensure that the rules maximise emission savings.
It added: “It is therefore crucial that the Government prioritises the removal of vehicles like HEVs that allow for a continued use of petrol and diesel burning without acting as a transitional vehicle towards an EV, only a plug-in hybrid can do that.
“We would therefore be supportive of a vehicle level CO2 cap. A vehicle level CO2 cap would ensure that the remaining PHEVs on the market achieve meaningful emissions reductions in the real world.
“This would need to be capped at 105gco2/km to ensure that manufacturers improve on their Phase 2 UF change, encouraging further innovation.”
The Government has already suggested they are considering CO2 emissions caps under certain circumstances.
The DfT stressed that vans could be affected by a similar rule after the 2030 car ban due to a lack of electric models available for owners at this stage.
The DfT stressed: “Instead, we will consider a primary CO2 requirement from 2030. Due to the differentiated nature of the van market, and the lack of hybrid alternative, a vehicle-level CO2 cap would have a disproportionate impact on larger vans.
“A vehicle-level cap could implicitly require larger models to become zero-emission.”