UPDATE: Eagle-eyed readers will notice the absence of Hyundai / Kia in EPA's list of fuel-efficient manufacturers. This is because of an on-going investigation by the EPA that Hyundai and Kia may have bloated their fuel-efficiency figures. However, based on preliminary data, Hyundai's values are 28.3 MPG (12.3 km/L) and Kia's at 25.8 MPG (10.96 km/L). This could mean Mazda could have its thrown usurped by Hyundai.

Despite not having a single gasoline-electric hybrid or plug-in electric vehicle in its line-up, Mazda has scored the title of being the most fuel-efficient automaker in the US according to the Environmental Protection Agency (EPA)'s Light Duty Fuel Economy Trends. Mazda improved its 2013 model year line-up to 27.5 MPG (11.69 km/L), a 0.5 MPG improvement compared to last year. At the same time, Mazda is also the lowest CO2 emitting car maker with just 324 grams of CO2, down 4 grams from last year.

“We are extremely proud of these findings made possible by Mazda’s suite of SKYACTIV Technologies,” says Steven Tan, President and CEO of Mazda Philippines. “This just shows that Mazda has taken the right path in investing on making major automobile components more efficient while recovering energy to bring back to the drive. With these results, Mazda has shown that it can be environmentally responsible without sacrificing its core identity of driving dynamism.”

Following Mazda is Honda with a 2013 model year average of 27.0 MPG (11.47 km/L). Volkswagen and Subaru are tied in third place with 26.2 MPG (11.13 km/L) model average.

1. *Hyundai - 28.3 MPG 
2. Mazda - 27.5 MPG
3. Honda - 27.0 MPG
4. Volkswagen - 26.2 MPG
5. Subaru - 26.2 MPG
6. *Kia - 25.8 MPG
7. Nissan - 25.3 MPG
8. Toyota - 25.2 MPG
9. BMW - 24.4 MPG
10. INDUSTRY AVERAGE - 24.0 MPG
11. Ford - 22.6 MPG
12. Daimler - 22.2 MPG
13. General Motors - 22.0 MPG
14. Chrysler / FIAT - 21.6 MPG