Nearly every press conference and presentation at the Mid-America Trucking Show in Louisville, Ky., last week seemed to mention natural gas.

Navistar even had natural-gas guru T. Boone Pickens himself on hand. In some presentations and casual discussions, however, there also was a feeling that perhaps it was being a bit too hyped. Fact is, it's still a niche market.

A sampling of the news:

Cummins announced it has begun development of a 15-liter heavy-duty, spark-ignited natural gas engine for on-highway applications. The move builds on the recent decision to produce a factory-built, dedicated natural gas version of the 12-liter ISX engine, the ISX12.

The ISX15 G will be based on the ISX15 diesel engine and will build on Cummins' spark-ignited, Stoichiometric cooled Exhaust Gas Recirculation technology. A simple, maintenance-free Three-Way Catalyst will be the only required exhaust aftertreatment. The engine will run on compressed natural gas, liquefied natural gas or biomethane. Cummins expects the ISX15 G to be in limited production by 2014.

Volvo Trucksadded a natural-gas fueled truck to its VNL lineup. When the natural gas option goes into full production, it will feature a 12-liter, 400 horsepower, 1,450 pounds-foot Cummins Westport ISX12 G engine that uses compressed or liquefied natural gas. Volvo is currently operating natural gas-powered VNL demonstrator trucks, with production beginning in conjunction with commercial availability of the 12-liter gas engine, which Cummins says should be in early 2013.

Kenworth is expanding its line of green products by offering the Cummins Westport ISX12 G heavy duty natural gas engine for use in regional haul, vocational and refuse markets.

Navistar'snew LoadStar severe-service low-cab-forward will have a Cummins ISL-G natural gas engine as one of its power options. (Kenworth already offers the 15-liter Westport HD and the 8.9-liter Cummins Westport ISL G as factory-installed options.)

Chevronintroduced a new premium oil for natural gas engines. One thing I learned talking to Chevron's Jim Gambill was that natural-gas engines typically have a much shorter drain interval than their diesel counterparts -- about a quarter as long, he said.

In an address to suppliers, Dan Sobic, Paccar executive vice president, said when you look at the fuel infrastructure in North America, today there are about 5,000 locations that serve diesel fuel. There are only about a thousand that have CNG or LNG, with LNG being about 150 of that total.

"The market probably today, best estimate is 8,000 trucks," he said. "Out of 220,000 to 240,000, that is still a small piece. I think the infrastructure has to continue to be developed, and secondly [we need to address] the upfront costs, whether it's through incentives or other means. Once you have the vehicle the efficiency's very good, but upfront can add $40,000 to $80,000 to the cost of a truck.

"Diesel fuel will still power trucks because it is the most efficient way to move trucks around."