A natural gas-fired Honda passenger vehicle was named the top-ranked clean vehicle for the eighth consecutive year earlier in February, and Chrysler Group LLC, a unit of Italy-based Fiat SpA, announced last Friday it was considering making a compressed natural gas (CNG) version of its popular Ram truck.

As part of the Chicago auto show, Chrysler officials said they were "exploring" the possibility of building some CNG Ram trucks, noting that the company is "eager and very interested" to expand natural gas-fueled capability to its truck brand. With a quarter ownership of Chrysler, Fiat is Europe's leading maker of CNG cars with 80% of the passenger market and 55% of the light commercial market for CNG vehicles.

Meanwhile, the Honda Civic GX once again has taken top honors in the annual environmental rankings produced by the American Council for an Energy Efficient Economy (ACEEE). The organization said Honda got the top ranking again despite the fact that so-called "Green Book" rating methods were changed to boost other clean transportation technologies.

The rest of the top 12 rankings were a mix of plug-in electric vehicles (EV), gasoline hybrids and what ACEEE called "ever-improving, conventional" gasoline vehicles.

Traditional vehicle advocates pointed to the relatively large number of conventional vehicles in the top 12 as a "testament" to how serious the manufacturers have taken the latest national and global emphasis on cleaner cars. In some cases the manufacturers are dubbing their new products as being "fuel sippers" that have improved transmission technology, weight savings and more sophisticated internal combustion engines.

Nissan's new Leaf EV was ranked second and the gasoline-powered Smart Fortwo was third. Hybrids had the next three rankings followed by Ford Fiesta SFE (super fuel efficient) and Chevrolet Cruze Eco.

ACEEE Transportation Director Therese Langer said EVs are the cleanest-running vehicles in terms of tailpipe emissions, but their upstream emissions can be substantial, depending on the source of the electricity used to fuel them. "As the U.S. power generation overall becomes cleaner, these vehicles' scores will rise," Langer said.

Chrysler indicated that it is looking at expanding its NGV offerings because the engines generally are cheaper to produce than other alternative fuel choices. The company is looking at aiming the CNG trucks at fleet operators because in most cases they would already have their own fueling stations.

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