HALF of the cabinet's luxury cars were replaced last year as the country was spiralling into economic disaster – but the government won't say how much it spent.

In 2008, a Mercedes S320, a Volvo S80, a Citroen C6, a BMW 525 and four Audi A6s rolled their way into the driveways of ministerial offices.

The departments of the taoiseach; agriculture; transport; justice; foreign affairs; community, rural and gael­tacht affairs; children; and education all benefited from the new vehicles.

Figures obtained under the Freedom of Information Act also reveal the heads of government departments each drive an average of 5,640km a month.

Top of the pile with an average monthly mileage of 9,293km is community, rural and gaeltacht affairs minister Eamon Ó Cuív.

As minister for justice, Brian Lenihan clocked up an average of around 7,997km every month, although figures provided for that department include his changeover with Dermot Ahern.

Micheál Martin in foreign affairs, Brendan Smith in agriculture and Noel Demp­sey in transport make up the rest of the top five ministers with the highest mileage.

Green Party minsters John Gormley and Eamon Ryan were among those with the lowest mileage, clocking up 3,766km and 3,500km per month respectively.

Brian Lenihan, while in the Department of Finance, averaged 3,500km a month; Willie O'Dea in Defence averaged 3,533km.

According to the Department of Justice, state cars are replaced when they are no longer considered economic to maintain due to their age and the distance they have travelled.

"Because of the age profile and mileage of the fleet at the time, a significant number of cars were replaced in 2007 and 2008," it said in a statement.

For "commercially sensitive" reasons, the department refuses to divulge how much is spent on each car and says there is no record of what they fetch when they are finally sold at auction.

"When the cars are replac­ed, they are invariably absorb­ed back into the fleet and are used as backup to cover periods when assigned cars are unavailable, such as for service, maintenance and repair periods," it said.

"The ultimate disposal of these cars is a matter for An Garda Siochána and is done by way of public auction in the same way that it disposes of other cars in the garda fleet when they have reached the end of their useful life."

Top Ministers Driving Distances Average kilometres per month

1. Eamon Ó Cuív (Rural & Gaeltacht Affairs) 9,293

2. Brian Lenihan and Dermot Ahern (both while in Justice) 7,997

3. Micheál Martin (Foreign Affairs) 6,875

4. Brendan Smith (Agriculture) 6,787

5. Noel Dempsey (Transport) 6,293

6. Taoiseach Brian Cowen 6,250, Tánaiste Mary Coughlan 6,250, Martin Cullen (Arts, Sports and Tourism) 6,250

7. Mary Harney (Health) 5,146

8. Batt O'Keefe (Education) 5,000

9. Mary Hanafin (Social, Family Affairs) 4,375

10. John Gormley (Environment) 3,766

11. Willie O'Dea (Defence) 3,533

12. Brian Lenihan (Finance) 3,500

13. Eamon Ryan (Communications) 3,293