Bulletproof, armoured V12 BMW 7-Series luxury sedans are already being used for C-1, the Prime Minister's dedicated vehicle, and for the Governor-General's primary security vehicle.

The long wheelbase Caprice had previously been the first choice for Comcar's "driver-with-vehicle" service provided across all the national capital cities.

However, when Holden ended its Australian vehicle production last year, the Commonwealth no longer had a source of locally-made cars which fit the criteria.

Comcar's current chauffeur fleet of 159 vehicles across Australia, all painted white and carrying the familiar Z number plate prefix, will be progressively replaced from this year in a contract estimated, once service costs are included, at well over $10 million.

BMW is seen as the front-runner because of its familiarity with the procurement process and its established relationship with the Department of Finance, which has narrowed the original field of 18 potential candidate cars down to a final seven.

The big benefit for the chances of the German brands is that the successful vehicle would be exempt from the federal government's luxury car tax (LCT).

LCT adds a 33 per cent tax to all cars above the $66,031 threshold.

The combination of fleet discounts and tax exemptions would cut as much as $30,000 off the list price paid by government for the Mercedes 220d (which retails for $96,000) and the BMW 520d (which retails for $94,900).

Judged on safety, value, fit for purpose, protocol and environmental consideration are cars from BMW, Mercedes-Benz, Toyota, and Hyundai's luxury car brand Genesis.

The seven contenders are:

The final seven all fit the government criteria for five-star safety and fit for purpose, but the value for money criteria creates a complex discussion between the initial savings of purchase cost balanced against whole-of-life ownership costs and resale value.

The Toyota and the Hyundai Genesis offer the cheapest initial purchase price but the German brands will be making much of their whole-of-life costs, which include low running costs and high resale value.

The potentially high resale value of the two German cars three or four years into their service life becomes a significant value-for-money consideration in the procurement process.

BMW has become fiercely aggressive in chasing fleet car business since the closure of Australia's car industry released state and federal governments from their requirement to favour locally-made cars for fleet use.

Last year after a lengthy assessment process, the BMW 5-Series turbo-diesel with a factory-produced "authority pack" was one of two car selected by NSW Police Highway Patrol to replace its fleet of Falcon and Commodore V8s.

NSW Police assessed 17 cars before selecting the BMW 530d and the Chrysler SRT8.

Comcar's current fleet of Holden Caprices will be "managed" and their service life extended to fit in with the replacement vehicle selection process and the time needed to get new white cars ordered and delivered.