Medium-duty fleet managers waiting for the next generation of low-emission diesel engines are aware that changes in fuel and engines are coming, but they are not quite sure how to prepare for it.

TOKYO — Several Japanese truck makers used the venue of the 38th Tokyo Motor Show here Nov. 2-5 to showcase emission-control systems they will use to meet the next round of heavy-duty diesel-engine emission standards, which are set to take effect next October.

ANAHEIM, Calif. — New truck technologies and tax benefits are two of several trends evident in the light- and medium-duty commercial truck market, a panel of suppliers said Sept. 23.

Unlike the heavy-duty truck sector, which can go years without seeing major changes in many of the Class 8 manufacturers’ units, the medium-duty sector always seems to offer at least a few models that have undergone major updates. That trend held true this year.

Medium-duty truck buyers satisfied with a stock truck should still be able to find lower-priced, pre-2004, emissions-compliant trucks on dealer lots. But those who wait are likely to find only vehicles with the latest generation of low-emissions diesel engines.

Model-year 2004 cargo vans are little changed from the 2003 models, on the outside at least. However, manufacturers are continuing a decade-long shift in marketing by adding accessories and products that appeal to the commercial buyers who now make the majority of full-size van purchases.

Ford Motor Co. said it would introduce a light-medium truck designed for commercial urban and suburban delivery markets in 2005.

Refinements rather than major makeovers are what most medium-duty truck manufacturers are offering in their 2004 models, although one manufacturer has redone its product line and all OEMs will sell new diesel engines built to comply with the federal government’s stricter emissions standards.

For several years, many medium-duty truck buyers have been fortunate enough to avoid, if not ignore, the turmoil that has roiled the heavy-duty diesel engine and truck business since 1998 as it rushed to meet lower diesel-emission standards on Oct. 1, 2002.

U.S. truck fleets are seeing the second coming of air disc brakes — whether they want to or not.