According to the Department for Transport (DfT), some 25.5 per cent of all government cars are now low-emission vehicles.
This comes ahead of plans to make the entire fleet fully zero emission by 2027.
Greening commitments set by Defra from 2021 to 2025 required that a minimum of a quarter of its car fleet be switched to ultra-low emission vehicles by the end of 2022.
The 25.5 per cent figure was reached in September, just 3 months ahead of schedule.
Technology and decarbonisation minister Jesse Norman said: "As the UK moves towards a cleaner transport network, the government is doing its part, with over 25 per cent of its central car fleet being battery-powered three months earlier than planned.
"It's critical that progress in decarbonising fleets is matched elsewhere. We will continue to forge ahead, to complete the switch by 2027 and help make the UK a world leader in decarbonisation."
The electric vehicle (EV) sector is currently experiencing year-on-year growth, with sales of second-hand pure electric cars in particular jumping by 44 per cent in the third quarter of 2022.
However, demand for EVs overall has fallen in recent months as rising energy prices and concerns about government policy have created a degree of wariness amongst consumers.
For the first time this month, one analysis showed that it actually cost electric car drivers more per mile on long journeys than people driving petrol cars.
The DfT has set out plans for a tenfold increase in the number of EV chargepoints in the UK by 2030 ahead of the ban on sales of new petrol and diesel cars. As of May last year, there were around 29,000 public plug-in points, which the DfT wants to increase to 325,000 by 2032.
The RAC has expressed concern that this increase will still not be sufficient considering the anticipated rapid adoption of new EVs by consumers.
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