Like other heavy-duty truck OEMs, Kenworth Truck Co. is staying on top of the alternative-fuel trend line in trucking that keeps pointing to natural gas as the front-runner. But the truck maker is clear that that’s not to say diesel power is going away anytime soon, nor should that be expected.

 “Diesel is of course well-established, but natural gas is a good fit for customers in specific applications,” explained Andy Douglas, national sales manager—specialty markets, speaking at a media ride-and drive event that highlighted natural-gas trucks on Friday at Kenworth’s truck plant in Chillicothe. OH.

“As an industry, we’ve been evangelizing about gas and its benefits,” continued Douglas. “And that’s fine. But [fleets have to look at] what are the total costs of running natural gas.” He said those costs include accessing or building fueling infrastructure as well as vehicle and tank maintenance.

According to Douglas, fleets are by and large still testing the waters when it comes to blue power. “Many of our customers that do buy NGVs [natural-gas vehicles] are also continuing to buy diesels also,” he advised.

On the other hand, Douglas pointed out that growth for natural gas is surely coming in part from major shippers that are committed as corporations to being green and in turn are pushing the motor carriers that serve them to switch to natural gas.

For example, he pointed to Proctor & Gamble, which Douglas advised has directed that 20% of its outbound shipments be handled by vehicles powered by natural gas. Fleets that can’t comply with the directive lose the business, while others, of course, gain it.

But the biggest group of NGV customers, according to Douglas, remain private fleets whose trucks typically return to a domicile daily for overnight refueling. One example he noted was Indianapolis-based beer wholesaler Monarch Beverage, which plans to have at least 85% of its fleet run on compressed natural gas.

Make no mistake, while diesel’s days as king of the road are far from numbered, Douglas did say as well that “there is an expanding footprint [for NGVs] among traditionally diesel fleets.

“As a market, natural gas is very much entering a mature state,” he continued, “given the product availability and that customers are buying these trucks across the country. Natural-gas [vehicle] market has seen huge growth from 2010 to 2012—rapid, coast-to-coast growth.”

Despite all that excitement about going green and saving green at the fuel pump with natural gas, Douglas cautioned that above all, “truck customers want to know what will be the lifecycle cost” vs. diesel.