ALLENTOWN, Pa. – When Mack introduced the original Econodyne engine in 1980, it brought to market an efficient engine that promised to deliver substantial fuel savings. Mack traditionalists hated it.

“It was initially not well received by the fleets, because they were used to the typical Mack engine which was all power, all the time,” admits David McKenna, director of powertrain sales with Mack. “They didn’t appreciate the lower torque curves of the original Econodyne.”

It has taken some time, but Mack has now come out with a fully integrated Super Econodyne powertrain package, which delivers on that demand for “all power, all the time” while providing even greater fuel savings than before.

Mack’s new Super Econodyne package consists of the MP8-455SE engine, mDrive automated manual transmission, Mack’s C125 drive axles and the software that connects all the dots and makes the fuel savings possible. It allows the engine to run as low as 1,160 rpm while cruising at 62 mph, a full 200-250 rpm lower than your typical MP8-455 Econodyne. This translates to a fuel savings of about 2%, Mack claims, or 3.5% when factoring in the efficient C125 axles. The results have impressed the US Environmental Protection Agency (EPA) so much that it has designated the Super Econodyne package an “innovative technology,” meaning Mack will earn credits towards compliance with the impending greenhouse gas emissions regulations for every truck it deploys with the SE powertrain pack.

Lowering the cruise speed of the engine from 1,380 rpm to 1,160 is made possible through the complete integration of the engine, transmission, axles and vehicle, McKenna claims.

“The only way you can do this is to be completely integrated,” he explains. “You need communication between the engine and transmission and the vehicle’s ECU. No manufacturer shares all its data with another manufacturer; it’s just not done. We share 100% of the information between the transmission, the engine and the ECU so we have 100% data exchange all of the time.”

Add to this the efficiency of Mack’s C125 drive axles, with a ratio of 2.66:1, and the fuel savings are significant. In fact, Mack claims independent testing has shown its C125 axle carriers to be 1.5% more fuel efficient than the next best in the industry, thanks to their spiral bevel gears, top-mounted design and a centrifugal power divider that works only when required.

Mack’s MP8 engine, its mDrive automated transmission and its C125 axle carriers are each impressive in their own right, but they are most impressive when viewed holistically as a complete package. That is the thinking behind the Super Econodyne powertrain, which provides the operator with a broader torque curve – a torque plateau, if you will – and gives Mack engineers more latitude in developing their shift strategies.

“There are two things you need to do,” McKenna says when describing the fuel-saving potential of the Super Econodyne package. “You have to make sure you have enough horsepower and torque to move the load and perform the work you’re asking the vehicle to do and the other trick is to do it at as low an rpm as possible without impacting gradeability or the ability to hold a cruise speed. We can all run engines at 1,100 rpm, but if it won’t get out of its own way, what good is it?”

The thinking behind the Super Econodyne all sounds very good in theory, but I wanted to take the Bulldog out on the highway for a good run to see how it performed over the undulating Pennsylvania hills near Allentown, home to Mack’s Customer Center. Mack hooked me up with a Pinnacle outfitted with the Super Econodyne package, pulling a flatdeck grossing about 77,000 lbs – an ideal weight and application for the SE pack.

Mack is very particular about the applications into which the new offering will initially be approved, but it’s best suited for mainstream, on-highway applications of up to 88,000 lbs. In time, the applicability of the technology may be expanded but for now, Mack wants to get it into the hands of mainstream linehaul operators where the fuel-saving benefits will be most pronounced. In fact, Mack’s so eager to get the package into the hands of fleets that it is offering it at no up-charge for the time being.

On the road
I drove the Mack Pinnacle with Super Econodyne package east along I-78 towards Newark, N.J. for a little over an hour and then back again, enjoying the rolling hills that tested the mDrive’s ability to hold top gear. Most of the time it did just that. I was never handicapped by the lower rpm and in fact, I passed my share of trucks on the uphill sections of the highway.

When the mDrive did drop a gear, it was non-disruptive. The mDrive’s console is mounted on the dash, which makes it easy to resist the temptation of trying to outthink the electronics. Incorporating a keypad console design rather than a traditional shifter is intended to minimize driver interference with gear selection.

“With the keypad, after a couple of days the driver forgets about it and that’s really what we want,” McKenna says. “We want to reduce the amount of manual inputs a driver makes with the transmission.”

Drivers who are familiar with Allison automatic transmissions will immediately be comfortable with the placement of the controls and the location makes it a little easier to slip out of the driver’s seat and into the sleeper cab.

The mDrive has been hugely popular since its 2010 introduction. Mack’s McKenna jokes he’s the only employee who can lie to the boss and keep his job, after predicting the transmission’s penetration might reach 12-15% the first year and maybe as much as 28% in a mature market.

“The second year, we were at 33% and this year we’re trending at 36% (of all Pinnacles sold),” McKenna says.

Based on the slick I-Shift transmission from Volvo, the mDrive isn’t a complete clone. McKenna says Mack chose not to incorporate some the functions of the I-Shift in hopes of providing a more robust transmission.

“We don’t want people confusing the two,” McKenna says, comparing the mDrive to a “roll up the sleeves and get the job done,” alternative. “A significant amount of the hardware is the same, but the software is definitely different.”

One of the most impressive features of the mDrive is Grade Gripper, which will hold the truck in position on a steep incline without rolling back. This function can be disabled via a toggle switch on the dash, but I’ve yet to come up with a good excuse for disabling it.

The mDrive is available in Fleet and Premium versions. The Fleet model limits a driver’s opportunities to intervene, allowing them only to hold the gear they’re already in. The Premium version allows drivers to override the transmission in certain situations. I was driving the Premium version and while it probably wasn’t necessary, I did enjoy having the option of dropping a gear while going downhill to coax a little more retardation out of the engine brake.

Speaking of the engine brake, Mack has incorporated some clever innovations into its PowerLeash Plus brake that’s exclusive to the mDrive. One such function is dubbed Cruise ’n Brake, which is designed to anticipate driver needs and engage accordingly while in cruise control. It will allow the truck to exceed its set cruise speed by 3 mph to better utilize gravity and prevent the brake from engaging too frequently.

There’s also a Set-Minus (Set-) setting for the engine brake, which allows the driver to select a cruise speed and then hold that speed all the way down a hill. Once the throttle is applied, the engine brake ‘forgets’ the chosen cruise speed, which can once again be set for the next hill. You can reduce the desired speed by tapping the toggle switch down or increase it by adding some throttle and then tapping the Set- button once again. It’s a smart engine brake with a lot of functionality and it’s also fun and easy to use once you get the hang of it and understand its capabilities.

The Super Econodyne package is also available with Smooth Cruise, a no-charge option that “desensitizes cruise control” and gradually ramps the truck’s speed back up to its set cruise speed.

“On the trucks we have today, when we go downhill it gives zero throttle and when you start going up the hill, it gives 100% power to the engine right away,” McKenna explains. “Smooth Cruise is more intuitive, it will actually roll on the throttle.”

The gradual re-engagement of the throttle while in cruise control was noticeable from behind the wheel and it addresses a long-running source of personal irritation. Most vehicles tend to race back up to the set cruise speed too aggressively for my liking, blowing away any fuel savings I’ve worked hard to achieve. Smooth Cruise will surely provide an impetus for drivers to run in cruise control more frequently, which in many cases is more efficient than working the foot feed.

Out on the highway, the Super Econodyne package did everything Mack said it would. It pulled strong at low rpms, provided ample power and ran particularly quiet, a welcomed by-product of the lower revving engine.

I was almost always in the Sweet Spot, as indicated by the double dollar signs on the in-cab display. I was flattered by the acknowledgement until I realized those dollar signs hardly ever disappeared, thanks to the extra wide speed spot afforded by the Super Econodyne. How wide?

Mack says the sweet spot on the Super Econodyne stretches from 1,050 to 1,500 rpm, compared to 1,200-1,500 rpm on the standard Econodyne.

This broader sweet spot covers road speeds of 58-80 mph in 12th gear. I remained in the sweet spot even when alternating between 10th and 12th gears and on the largest hills along my route I was never a moving chicane that other trucks or even cars were forced to avoid.

Peak torque of 1,760 lb.-ft. is available nearly all the time and a whopping 1,400 lb.-ft. is available right down to 900 rpm. This abundance of torque at low rpms is a key differentiator between Mack’s former Econodyne engine and the Super Econodyne package available today.

The Super Econodyne provides a relaxed driving experience, which Mack thinks will translate to improved safety. It’s not a nonsensical suggestion.

And how about the Pinnacle itself? With the downturn in the construction sector, Mack has had plenty of time to turn its attention to its highway products. It has done just that and officials say they feel the company has discovered a healthier balance between its highway and vocational product lines. Today’s Pinnacle isn’t your old man’s Mack truck. It’s a really, really nicely appointed vehicle with plenty of storage and an intuitive layout.

The truck I drove featured a stylish Trim Level 3 interior with button-tuck ceiling. The leather seats and steering wheel are stylish in an old-school way, comfortable to use and easy to position. Visibility over the hood is fantastic. The truck I drove came with a full complement of safety-related driver aids including Bendix Blindspotter and its Wingman Active Cruise with Braking (did my reputation precede me?)

The Pinnacle I drove was adorned with a gold bulldog on the hood, meaning it was equipped with a fully integrated Mack powertrain. With the Super Econodye package now available – essentially for free – you could be seeing more of those gold bulldogs in the not-too-distant future.