PHOENIX — After a model life of nearly 30 years, Kenworth is updating its Class 5 medium-duty vehicles through Class 8, with the introduction of four all-new models: the T180, T280, T380 and T480.

RENTON, Wash. — Kenworth Truck Co. spotlighted the aerodynamic and interior upgrades to its T680 Next Gen Class 8 during a small media event that began at its proving grounds here, then shifted to a 40-mile test drive during which both the day cab and …

When exhaust-gas recirculation became the technology to meet the heavy-duty truck emissions standards, underhood temperatures skyrocketed and put extreme pressure on cooling fan drives and belts, .Fleets now can spec a variety of variable-­speed and el…