Nov 1, 2007 12:00 PM, By David A Kolman

Having an opportunity to drive a loaded DuraStar Hybrid, I was taken aback by its performance. Never having driven any type of hybrid medium duty truck, I figured it would need to be driven differently, and would be sluggish. Such was not the case.

The truck started out with plenty of power, because at virtually 0 rpm, 60 horsepower and up to 300 lb-ft of torque is blended into the driveline instantaneously. There was a lot less noise as the diesel engine was at idle maintaining engine cooling and accessory loads.

The hybrid electric system automatically switches to diesel power as demand is requested by the driver. I discovered that this happens based on vehicle weight and the speed demanded.

The only indication of the switch to diesel power was an increase in noise from the engine “coming on” off of idle. There was no noticeable change in the truck's operation. All shifts from the automated transmission were relatively smooth.

I found the hybrid electric system is best suited to inter-city type start-and-stop applications such as pick-up and delivery. That is because the system works invisibly in such operations to save fuel while delivering performance.

I appreciated the regenerative braking feature because it enhances stopping power by using the electric motor to slow the vehicle. I used the truck brakes less often, and that helps reduce brake wear.

Because the DuraStar Hybrids have a parallel hybrid system, the diesel engine remains fully functional in the event that the hybrid system should need to “go offline” for any reason.