Australian: ASSISTANT Treasurer Chris Bowen has left the door open to exempting petrol from a national emissions trading scheme. Mr Bowen confirmed yesterday that Kevin Rudd’s concern over petrol prices putting pressure on family budgets would be a consideration in the design of any emissions trading scheme. But he played down reports of Easter price hikes by petrol retailers, suggesting the increases were within normal fluctuations. "Petrol is a very important commodity for …