General Motors is celebrating being the first U.S. automaker to sell more than one million vehicles in a single year capable of 30 mpg or more on the highway.

Sales of 13 different 30 mpg-capable models totaled one million units in 2012, with four models--the Spark, Cruze, Sonic and Volt--managing more than 30 mpg combined.

A host of smaller, more efficient vehicles in GM's lineup has seen its average fuel economy creep up over the last few years. Two models, the Chevrolet Cruze Eco and Chevrolet Sonic, break the 40 mpg mark in highway driving.

Around 40 percent of GM's lineup now uses four-cylinder engines--ten percent more than 2010's range--and GM expects 39 percent of 2012's sales to be mini, small and compact cars, when the figures emerge.

Flagship of GM's fuel-efficient range is the Chevrolet Volt, with almost 21,000 units finding homes in 2012 by the end of November. Volt sales climbed steadily in almost every month of 2012, while also attracting praise from customers--92 percent say they'd buy another.

Meeting 30 mpg highway might not seem that impressive, but it represents the progress many U.S. carmakers have made to improving gas mileage over the last several years.

It's also a more realistic target to shout about than Hyundai's claims about a range of 40 mpg cars--given the recent debacle over mis-stated EPA fuel numbers.

Still, there's always progress to be made. 30 mpg is a start, but there's plenty of room for improvement...


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