Could More Fuel-Efficient Engines Lead to More Global Warming? (image) American Chemical Society Share Print E-Mail Caption Cars with newer gasoline direct injection (GDI) engines emit more black carbon than those with traditional port fuel injection (PFI) engines, but installing filters could mitigate this. Credit American Chemical Society Usage Restrictions None Share Print E-Mail Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.