Pinnacle of Performance

Steve Sturgess | June 01, 2012

As I climbed into the truck, I noticed the absence of a gear lever and a clutch. I also noticed the shift pad on the wing dash, and with neutral selected, I fired up the engine and we were on our way.


Threading my way out of the Kentucky Fairgrounds, I was impressed by the way the transmission picked up gears yet idled easily in traffic. Adjusting to this vehicle was no problem because the seating provides an excellent view over the sloping hood, and the well-placed mirrors complete the comprehensive visibility. Once on the freeway on-ramp, I hit the throttle to get up to speed — a simple task with the automated transmission. I dialed in the cruise control and sat back to enjoy the ride.

The mDrive is impressive technology. It doesn’t just respond to the engine; it drives it. Gears are selected according to road conditions — the transmission even has an inclinometer so that it knows if the truck is going up or downhill. It knows what the driver wants through the throttle position, and it tells the engine what is needed. Starting out, it gradually closes the clutch for an impeccable response to the first squeeze of the throttle pedal. When it’s time to shift gears, the transmission commands the engine to back off and break the torque flow. The transmission then float-shifts to the next gear, exactly matching engine revs to smoothly swap gears.

In an upshift, the transmission may call on the engine brake to slow the rpms, snapping shifts through faster than even the best driver could. I found this out first-hand at the Customer Care Center test track on day two when accelerating up a 10-percent test hill from a standstill. The Mack just picked up gears as it accelerated away, block shifting one to three, then four and five to make the most of the transmission’s capabilities.

On the highway, such an extreme start was never necessary, but the transmission would often skip gears, either to make the most of the acceleration or to bring in the Powerleash engine brake for maximum retarding. At the same time, it optimized fuel economy. One of the big pluses of all automated transmissions is that they go a long way to equalizing the driving performance of different drivers in a fleet. It’s often said that the difference between a top economy driver and the worst may impact fuel use by as much as 30 percent. With an automated shift, this can be reduced to only a few percentage points.

As we started out, the numbers on the dash display climbed to a very creditable 7.3 mpg as we negotiated the hills of Kentucky. Then as we got into the serious climbs of West Virginia into Allentown, fuel economy crept back to 6.9 mpg. But that’s not at all bad given the heavy load and the mountains.

We started out mid-morning and took a break after four hours. Then, after lunch, we climbed back into the truck with another eight hours ahead of us through the mountains. A cup of coffee at the Pilot Truck Stop on Greencastle Pike in Hagerstown, Md., boosted my energy, and I pulled up at the Customer Care Center gates feeling fresher and more alert than I had at the lunchtime stop. That says a lot for the Mack and speaks well of the transmission. With the task of shifting handled automatically, I was far more relaxed through the drive and less physically tired than I would have been wrestling the shift lever as we journeyed through the mountains.

What’s really nice is the way the mDrive handles the unexpected, like a car slowing in front of the truck or an obstacle in a corner. As a driver, you can deal with the situation, confident that when you walk on the throttle again, you’re going to be in the right gear to step smartly off again.


The Pinnacle has good driver’s seat travel and an adjustable steering column, so it’s easy to set the driving position to the pedals and get the wheel just right. The dash is excellent, with top gauges shaped to fit within the arc of the wheel. So with a great view out and information clearly displayed, it really was a cruise with the transmission dropping gears on the long climbs — sometimes one, sometimes two, almost never three — as the Mack MP8 really gets down and goes, especially with the boost feature.

With the task of shifting handled automatically, I was far more relaxed through the drive and less physically tired than I would have been wrestling the shift lever as we journeyed through the mountains.

The driver display is a triumph. The screens are clear and well organized. Moreover, the column stalk has only an up/down rocker, and the enter and escape buttons are so intuitive anyone can use them within seconds.

The leather seats sit nicely far apart in this wide cab, so even with armrests there’s a full 14 inches of walk-through to the sleeper. However, because the center console stack has big cup holders, a handy shelf and a large storage bin, the seats have to be pushed back when standing up from either the driver or passenger seat.

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