Sales of medium- and heavy-duty trucks slipped 8.4% in the U.S. in August, the sixth monthly loss for the group this year, WardsAuto data shows.

Only Classes 4 and 7 posted gains over like-2012, as nearly every group’s performance could be traced to minor or major losses by beleaguered Illinois-based truck maker International.

Class 8 sales fell 10.6% as all but two manufacturers declined from year-ago. PACCAR’s Kenworth and the Volvo Truck brand saw August sales rise 7.6% and 11.2%, respectively.

Daimler’s Western Star suffered the biggest drop in the heavy-duty sector, down 37.4%, just ahead of International’s 30.6% decline.

Medium-duty sales fell 5.7% in August due to Class 5 and 6 declines.

Despite gains at nearly every truck manufacturer, Class 7 sales rose a scant 2.6%. No.2 volume-leader International’s 32.0% slide tempered gains at No.1 Daimler, whose sales rose 21.2% last month. Hino saw sales climb 42.3% and Kenworth deliveries jumped 50.7%.

International was the leading culprit in Class 6’s 19.7% drop. The former No.1 seller in the group lost 61.8% of its August 2012 daily volume, ceding the top spot to Daimler, which saw sales rise 23.3% last month.

Smaller-volume Class 6 players suffering declines included Kenworth, down 39.5%, and Hino, off 17.2% from year-ago.

International also had a 60%-plus loss in Class 5 that, along with a 5.8% dip at volume-leader Ford, caused group sales to slip 4.8%.

Daimler’s Mitsubishi Fuso was the leading gainer in Class 5 sales, up 62.9%, and PACCAR posted a 20.5% increase, although on small volume.

The 23.8% climb in Class 4 deliveries was the best performance last month among any big- or medium-truck group, thanks largely to Isuzu’s 128.3% jump in domestically built models. The group’s other entrants, Ford and Mitsubishi Fuso, also recorded positive results.

Isuzu’s imported units posted the only Class 4 decline, down 4.8%.

Through August, sales of medium- and heavy-duty trucks in the U.S. were off 3.3% from the same period year-ago to 225,355 units.

As has been the case in recent months, both inventory and days’ supply fell in August.

Class 8 had 35,548 units in stock at the end of last month, a 65 days’ supply. That compares with 41,151 units, or 67 days’, year-ago.

Medium-duty inventory of 38,548, an 80 days’ supply, was down from 42,621, or 83 days, in like-2012.

In other big-truck news:

  • Following disappointing third-quarter results, Navistar International plans to cut 500 jobs globally by the end of October, says the Chicago Tribune.
    Navistar lost $247 million in its third quarter ended July 31. It posted an $84 million profit year-ago. The truck maker blames a slower-than-expected recovery in its business and a loss of market share for the poor performance.
    Navistar says it will take until 2014 to return to profitability.
  • Volvo showed off its latest VM models for Brazil and Latin America earlier this month. The fourth generation of the trucks, first introduced in 2003, offer optional 4-axle configurations for higher load capacity.
    The 4-axle VMs can be ordered with 270-hp or 330-hp engines and 6- to 12-speed gearboxes, and in 4x2, 6x2 and 6x4 configurations.
    The trucks carry over styling updates already seen in European models, including V-shaped light-emitting-diode daytime running lights and restyled bumpers that have “more modern, robust materials,” Volvo says.

cschweinsberg@wardsauto.com