The Commission is postponing a decision on how to assess the climatic impact of non-conventional sources of transport fuel such as tar sands and oil shale. A decision was expected in June, but Brussels has ordered an assessment of the impact of giving high-carbon sources a higher climate rating, which means no final judgement will be made until next year. The postponement came just days after T&E published a study saying reducing greenhouse gas emissions from petrol and diesel production will cost less to administer than the oil industry says.