Defra is replacing a significant proportion of its diesel company car fleet with Toyota Auris hybrid electric models.
The changeover by the government department responsible for the environment, food and rural affairs, is expected to cover more than 400 vehicles.
It is already underway and will continue throughout 2018 in a rolling replacement process.
The cars will be used by four Defra organisations: Environment Agency, Marine Management Organisation, Rural Payments Agency and Animal and Plant Health Agency.
Jim Gregory, strategic fleet manager for Defra Group Fleet Services, said: “The cars from these four Defra organisations already represent one of the lowest CO2 emitting fleets in the UK and we have reduced nitrogen oxide gases (NOx) emissions, linked to respiratory illness, by nearly 10%, and CO2 by nearly 30%, across our 7,000 cars, commercial vehicles, plant and machinery.
"We have challenged ourselves to go even further by buying only hybrid or electric vehicles from 2025, replacing our current fleet of diesels with cleaner vehicles and setting targets for NOx as well as CO2 emissions.
“We’re balancing a challenging ambition against the needs of our vehicle users, while keeping a close eye on new and emerging technology which can help us reduce our harmful emissions even further without increasing our costs.”