The lucrative deal passed over the two best-selling electric cars in the ACT and across the country - the Tesla Model 3 and Model Y - in favour of the far more expensive BMWs.

These luxury BMWs have courted controversy for their "bold" styling and blunt, towering grilles. The vehicles have attracted only 71 customers so far this year so the federal government order is a huge boost to the luxury German car importer's coffers.

The Department of Finance chose the BMW iX40 and iX50 SUVs after assessing 40 different models. It was vague about the extensive charging infrastructure that would be needed at its Dairy Road depot where most of the BMWs will be stored, but have sought to provide assurances that this will be in place as the leased cars arrive.

The iX electric models will replace the turbo-diesel 6-Series SUVs, which were chosen by the department under the previous Liberal National government.

In a statement, COMCAR said the EVs will be used to "carry out all aspects of COMCAR's operations, including general transport of parliamentarians and other clients, the parliamentary shuttle and VIP/Guest of Government visits and major events".

The current fleet includes 92 leased BMW 620d diesel-powered sedans and 45 Toyota Camry Hybrid cars.

The iX40 retails for about $147,000 and the longer-range iX50 for about $193,000. According to drive.com, the BMW iX40 "drives and rides like a truly luxurious car, and it pampers occupants like none of its rivals".

COMCAR said the new EVs would enter service from mid-year, with the full transition to be completed by mid-2024.

COMCAR whittled down an initial list of 40 car models to 14 vehicles for preliminary physical assessment.

Of these, nine models were selected to be put through their paces on a closed circuit track and on the open road. In addition to the BMW vehicles, other models assessed included Polestar 2, Genesis GV60 and GV70, Kia EV6, Tesla Model 3 and Model Y and Hyundai's Ioniq 5.

The agency said it assessed the vehicles for battery consumption, charging capabilities, vehicle handling and maneuverability, comfort, ease of access, carrying capacity and potential integration with COMCAR's Automated Resource System.

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"The overall assessment identified the BMW iX40 as the only vehicle that is suitable for all aspects of COMCAR's operations," the agency said, adding that a small number of BMW iX50s, which have a longer range, will also be purchased.

COMCAR admitted the upfront cost - which it did not specify - will be greater than for conventionally-powered vehicles, but said it expected to make savings in running costs, including fuel and maintenance.

The move is taking place as part of a transition to lower-emission vehicles across the broader Commonwealth vehicle fleet.

With a tranche of current leases ending this year, the government is aiming for 75 per cent of its new vehicle leases to be low emissions by 2025.