The EU's executive Commission proposed carmakers be required to reduce carbon dioxide (CO2) emissions from new cars sold in Europe to an average 130 grams per kilometre by 2012. But Sergio Marchionne, chief executive of Italian car maker Fiat and head of the ACEA, told a business seminar:
"It is prohibitively expensive to achieve a target of 130 grams per km through vehicle technology only. It is unrealistic that this can be done by 2012.
"The announced legislative framework will not be ready before 2009. This leaves the industry too little time to apply it by 2012. The cars of 2012 are being designed today," he said.
ACEA represents manufacturers including BMW, DaimlerChrysler, Porsche, Fiat and Renault.
The Commission's proposal is part of the European Union's efforts to fight climate change.