If the latest news out of China is any indication, Ford has little to worry about. The Associated Press reports that Ford said sales of Ford-brand vehicles, including imports, rose 135 percent to 44,439 vehicles there in January.

General Motors said earlier that its sales of GM-brand vehicles in China rose 26 percent in January to a monthly record of 310,765.

Consumer Reports magazine tested a wide variety of these turbocharged vehicles, and even contests the EPA fuel-economy estimates on the vehicles, saying the cars didn’t match up.

General Motors also released a statement implying that the testers might have driven more aggressively than the average Cruze owner does. “If you have a heavy foot on a turbocharged engine, you're not necessarily going to see a lot of fuel economy benefits.”

Since the middle of 2009, Ford has been aggressively marketing its EcoBoost engines, which feature a turbocharger and promise greater fuel efficiency. The company has sold more than a half million models with EcoBoost engines.

"Our customers are very happy with their EcoBoost vehicles," said Sherwood. Many of those customers paid between $700 and $900 extra to buy a model with an EcoBoost engine.

Stricter government policies are putting pressure on automakers to improve mileage. As standards change over the next 7 years, results will reveal which manufacturers make the grade.

Ford finished Thursday down about 1 percent while GM was down about 0.2 percent.