Hyundai posts biggest gas-mileage gains

With gas prices rising, it only makes sense that cars and trucks are getting progressively more fuel-efficient. But how much?

Based on vehicles sold in July compared with a year earlier, new vehicles are 1.5 miles per gallon more efficient, according to TrueCar.com, which tracks new-vehicle sales.

It's not just that vehicles are being made more efficient. Rather, it's that customers are demanding better gas mileage and seek out particular models that have made the biggest gains -- which helps explain the fuel-mileage gains.

"Manufacturers have been responding by offering a larger mix of smaller vehicles and improving efficiencies on their existing larger vehicle engines, as evidenced by the significant improvement in TrueMPG in the recent years," said Jesse Toprak, a TrueCar vice president.

But gas mileage gains, it turns out, vary by maker.

The gas mileage for Fords sold last month averaged 22 miles per gallon, compared with 20.5 mpg a year ago. Ford's 1.5 mpg gain was almost twice the 0.7 mpg gain at Chrysler and 0.6 mpg gain at General Motors, based on vehicles sold last month compared to the year before, TrueCar.com says.

The biggest gain was Hyundai, at 2.5 mpg. It's also the brand with the highest overall gas mileage of 27.8 mpg. Toyota rose 1.4 mpg to 24.2 mpg and Honda was up 1.8 mpg to 25 mpg.