Sydney  - It's that time of the year again for Australians who drive a company car.

June is the end of the fiscal year and the higher the mileage, the greater the tax break that can be claimed. So the southern hemisphere autumn is the time for lots of aimless driving just to break that threshold and get into the top bracket for deductions.

The privately funded Australian Conservation Foundation (ACF) says it's ridiculous that the taxpayer is helping fund the company car.

Over 18 per cent of motoring is by company car. It creates the same amount of greenhouse gas pollution as a coal-fired power station.

"It's over 1 billion of subsidy that you and I, taxpayers, pay for this car use," ACF director Don Henry said.

Government figures show the tax break for the company car is costing 1.5 billion Australian dollars (1.4 billion US dollars) a year. Unless the tax break is revisited, by 2010 the annual cost will be over 2 billion dollars.

"In this modern day and age, we can't afford (company cars) and we should shift some of that money onto investments that help us have a cleaner and more efficient economy," Henry said. "That's not only going to give our children a better future, it will help drive productivity in our economy as well." (dpa)