Test Drive: Mack Pinnacle

The test truck was a 70-inch condo 2007 Mack Pinnacle, which was hooked to a 53-foot dry van loaded with concrete blocks.

With its 2007 Pinnacle, Mack Trucks plans to get “back in the highway business,” says Highway Product Marketing Manager Jerry Warmkessel, “and it’s going to stay that way.”

To evaluate this claim, I test-drove one of the Pinnacle’s five models, beginning at the Las Vegas speedway on I-15 just north of town. I selected a bright yellow, 70-inch condo with a 239-inch wheelbase and 112-inch BBC, hooked to a 53-foot dry van loaded with about 36,000 pounds of well-secured concrete blocks for a gross weight of 69,920 pounds.

It was a clear, dry day in June with moderate traffic.

The truck was powered by Mack’s new 13-liter Maxicruise MP8 with 415 horsepower at 1,700 rpm and 1,560 pounds-feet torque at 1,100-1,200 rpm, coupled with an Eaton 10-speed, fully automatic Ultrashift transmission and a 3.73 rear axle.

The Pinnacle and the MP8 are part of a trend of innovative response to fuel costs and environmental regulations.

“We’ve done more research than at any other time in the company’s history,” Warmkessel says.

For example, the MP8 comes also in an Econodyne package, intended for mostly flat interstate and less-than-truckload applications. Both the Econodyne and Maxicruise MP8s offer up to 485 horsepower and 1,660 pounds-feet of torque.

“These are the right engines for fuel economy and power,” says Powertrain Sales and Marketing Chief David McKenna, pointing out that the MP8 has the highest power density – horsepower per cubic liter – in the industry at 32-37 horsepower per liter. All MP8s are configured to work well with 6-, 9-, 10-, 13- or 18-speed manual or automatic transmissions. McKenna says Mack expects significant fuel-economy improvements in the MP8: about 4 percent better than the Mack engines the MP8 replaces.

This is partly on account of the Pinnacle’s aerodynamics, which also afford excellent visibility. I could see cars on the right when they were even with the sloped hood’s highest point, though I’m 6’4″ and keep the seat high.

Also among the truck’s features are a wider frame, increased engine-compartment airflow to cool the hotter-running 2007 engines and improved maneuverability due to a 50-degree steering-wheel angle.

For driver comfort, the Pinnacle has an insulated, quieter cab.

“We’re confident it’s absolutely the quietest cab in the industry,” Warmkessel says.

The Pinnacle also has “even-plane” throttle and brake pedals, side by side for easier and safer operation. The steering column has a position for every driver. The seats also feature numerous driver-comfort adjustments, including an attached automatic gearshift platform that swivels around behind the seat and out of the way.

“Ninety-eight percent of the population will fit into and operate this truck,” Warmkessel says.

The dash of my test truck featured Mack’s driver information display screen, 14 gauges, and dozens of switches and controls, all readable at a glance and/or easy to reach and operate. The cup holders were sturdy and deep enough to work through potholes, swerves and hard brakes.

I didn’t have Mack’s optional CoPilot, an electronic driver tool with a large, easy-to-read screen, but we did have Mack’s optional Grand Touring Cobalt Blue cloth and Ultraleather trim package and the auxiliary power system, designed by Overdrive magazine’s 2005 Trucker of the Year Robert Jordan. The system has two units, both under the bunk: a Webasto heater, which uses a half gallon of diesel during a 10-hour break, and a 10,000-BTU air conditioner run by rechargeable, deep-cell batteries guaranteed for 10 years.

But there is plenty more room under the bunk. There also are various cabinets and shelves and a cavernous over-cab attic that easily doubles the Pinnacle’s storage space.

Other available options include wireless tire-pressure monitoring, door mounted cameras to eliminate blind spots, and a global positioning system that provides maps with information on road conditions, bridge heights and points of interest.

Mack’s Road Stability system, which prevents rollovers and jackknifing, is standard.

“We’re the first original manufacturer in the world to have this standard,” Warmkessel says.

After I familiarized myself with the controls, I headed north on I-15 at the 54 entrance ramp, which put us right on a 2-mile, 2.5 percent upslope. After turning onto the ramp at about 15 miles an hour, I mashed the throttle and held it down. The MP8 got us to 64 miles an hour and made it to 10th gear before the slope’s summit: not bad at all for 415 horsepower.

The speed limit on I-15 in Nevada is 75 miles an hour, so after a few miles at 65 mph to get a feel for the Pinnacle, I got us up to speed.

I was surprised by the performance of the 415-horsepower MP8. The Pinnacle was storming the considerable hills north of Las Vegas on I-15, and the MP8 was still new – far from broken in, when it will deliver its peak horsepower. During the entire 200-mile test-drive, the hills caused the Eaton transmission to drop below ninth just twice: once for a particularly steep climb, and once when we got trapped behind a triple-trailer rig slowed to about 15 mph on a long, steep hill. The only other things to slow the Pinnacle were its air brakes and Mack’s PowerLeash engine brake, which also worked exceptionally well.

On one occasion I topped a hill in the left lane, got quickly back up to 75 mph and rounded a medium-hard right curve – right onto a 5-6 percent mile-long downslope. The Pinnacle’s inertia from the right curve, along with the left lane’s slight incline toward the shoulder, bore down on the Pinnacle, pushing it toward the left shoulder. Gravity took hold of the truck, too, and we shot down the hill.

No problem: I tapped the brake to disengage the cruise control and engage the PowerLeash. From inside the insulated cab, I couldn’t hear the PowerLeash at work unless I consciously listened for it, but it was powerful enough to break the 35-ton rig’s momentum.

The Pinnacle straightened up and slowed down, and within five seconds we were tucked neatly into the right-hand lane. I feathered the throttle on the way down so the PowerLeash wouldn’t slow us down too much.

The MP8 is also prepared to handle tighter emissions regulations. All gearing has been moved from the front to the back of the engine. This narrows the engine’s front, allowing for more airflow and greater cooling, and it also puts the gearing near the flywheel, decreasing engine vibrations. Remove four bolts under the dash to access the rear of the engine from inside the cab. The MP8’s crankcase breather has a filter so its fumes comply with ’07 emissions regulations.

Along that line, Mack cleans the MP8’s exhaust with cooled exhaust gas recirculation.

The aftertreatment system includes a diesel particulate filter, the heart of which is a platinum-coated ceramic catalyst. The Pinnacle has two optional DPFs, both vertical: the MackCap, just forward of the passenger-side fuel tank, and the Back-of-Cab model. Both last the life of the engine and will last 150,000 miles before service.

Mack is up front about the system’s cost.

“The kind of engineering that went into these vehicles is not free,” says Vice President of Marketing Tom Kelly. “A cleaner environment is also not free, and I won’t apologize for that.”

Kelly says Mack’s costs for meeting EPA standards “will be competitive” – roughly $8,000 per truck, he says, then adding: “A street price really hasn’t emerged yet.”

But consider the fuel mileage you’ll get in this truck: on this trip, 7.9 mpg, according to the Pinnacle’s driver information screen. This is impressive, considering we were at 70,000 pounds and running hard through the mountains northeast of Las Vegas.

I continued north on I-15, growing more impressed with the MP8’s pulling power and engine brake. At the first exit ramp across the Arizona state line, I let the PowerLeash slow the vehicle to about 30 miles an hour before I feathered the throttle so we’d make it to the stop sign.

I stopped for some photos, then headed back down the only hill the PowerLeash could not handle on its own (air-brake assistance was required).

But the MP8 continued to perform. I’ve driven engines with ratings of 300 to 600-plus horsepower. The general rule is that 415 will get a heavily loaded truck through the mountains, but it’ll slow down on the steeper hills.

Apparently the MP8 hasn’t heard that rule. I set the cruise control at 75 again. It was about 2:15 p.m. We were 80 miles from the endpoint and were due back by 3:30. We arrived 10 minutes early.

Test Drive Specs
Truck: Mack Pinnacle Axle-Back 70-inch high-rise sleeper
Engine: 415 horsepower Mack Maxicruise MP8
Transmission: Eaton-Fuller fully automatic 10-speed Ultrashift
Rear Axle Differential: 3:73
Front Axle: Mack FXL 12,000 lb.
Suspension: Mack MaxLite 40 EZ Air Ride
Wheelbase: 239 inches
BBC: 112 inches
Interior Trim: Cobalt Blue Cloth/Ultraleather
Tractor Weight: 19,300 lbs.
Tractor/trailer Weight (empty): 33,960 lbs.
Tractor/trailer Weight (loaded): 69,920 lbs.
Fuel Mileage: 7.9 miles per gallon
Test Drive Length: 200 miles

The Business Manual for Owner-Operators
Overdrive editors and ATBS present the industry’s best manual for prospective and committed owner-operators. You’ll find exceptional depth on many issues in the 2022 edition of Partners in Business.
Partners in Business Issue Cover