"Only four out of 11 carmakers are forecast to meet the EU 2021 CO2 emission target, with the rest facing significant fines," researchers from British firm PA Consulting said in a statement today.
European Union nations agreed in 2014 that carmakers should limit CO2 emissions to 95 grammes per kilometre across their entire model range within seven years.
The figure for 2015 stood at some 130 grammes per kilometre on average.
"Most carmakers will face penalties," especially German manufacturers which often offer larger, more polluting engines, the study authors forecast.
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"There is nothing less than a revolution facing the car industry and those manufacturers who fail to keep up face potential fines in the billions," PA auto expert Thomas Goettle said.
Germany's BMW, Volkswagen and Daimler, US-based Ford, Italian-American Chrysler, France's PSA and South Korea's Hyundai will be unable to get their emissions under control by the deadline, according to the study.
As the world's largest carmaker and owner of Audi and Porsche, Volkswagen could suffer a 1.7-billion-euro penalty, while Brussels' bill for Fiat Chrysler could reach 1.2 billion, the forecasts suggest.
Sweden's Volvo, Japan's Toyota, Franco-Japanese Renault- Nissan and Jaguar Land Rover are all predicted to meet CO2 targets.
German carmakers have announced a flood of electric models for the coming years as emissions scandals have tarnished the image of diesel, which they had bet on to reduce the CO2 toll.