Nuts and Bolts
Technical highlights for the 2007 Acura MDX include an all-new, 300-horsepower V6 engine, a Super Handling AWD system, an Active Damping suspension, and the largest wheels and tires ever offered by the company.
Despite consumer concerns about fuel economy, Acura has sacrificed a few MPGs for added HPs. There still isn’t a V8 engine in the luxury automaker’s arsenal, but the 2007 Acura MDX really doesn’t need one thanks to an all-new 3.7-liter V6 with variable valve timing. Driver Dads take note: Boasting a 6,500 rpm redline, oil-jet cooling, aluminum cylinder sleeves, a high-flow exhaust system, and a 5,000-pound towing capacity, this engine generates an even 300 horsepower at 6,000 rpm and 275 lb.-ft. of torque at 5,000 rpm. For those keeping score, that’s 47 more horsepower and 25 added lb.-ft. of torque, plus 2,000 pounds of extra towing capacity. Also, under hard acceleration, the MDX is tuned to deliver a sporty intake growl but remains quiet when cruising. Stylish Moms need only to know that the new MDX is faster, and that means it’s easier to get on the freeway or merge with traffic.
Acura hooks this new engine to a grade-logic five-speed transmission with a shift-hold feature and sequential SportShift. Huh? Whaa? Grade logic is transmission software that can tell if you’re driving up or down a hill, and it holds a lower gear to provide extra power and to keep the transmission from shifting up and down while climbing, or to add engine braking while descending. The shift-hold control engages automatically using similar software that determines when this is appropriate – usually when Driver Dad is introducing the Munchkins to the laws of physics.
The transmission delivers engine power to Acura’s Super Handling All-Wheel Drive (SH-AWD), a sophisticated AWD system that first debuted on the current RL luxury sedan. Under normal conditions, the power is split 90 percent to the front wheels and 10 percent to the rear wheels, but under certain conditions as much as 70 percent can flow to the rear wheels with 30 percent going to the front wheels. At this extreme, the “Super Handling” part of the equation comes in to play. Acura’s unique AWD system can deliver that 70 percent of engine power to one or the other of the rear wheels to maintain maximum grip and performance. The system works brilliantly, as we learned on a rain-soaked race track. More on that later.
Acura’s European vacation gave its engineers newfound appreciation for tight, responsive steering, line trace (the car’s ability to stay on the intended path), and proper suspension tuning. Thus, the 2007 Acura MDX gets torque-sensing, variable rack-and-pinion steering guiding standard 18-inch wheels connected to a front strut suspension and a multi-link design in the back that manages to preserve a four-foot cargo area width between the wheel wells for carrying the all-important sheet of plywood. Added wheel travel and greater use of aluminum in the front suspension adds up to a more compliant ride and a reduction in unsprung weight, and Acura says it has also improved pitching and linearity of roll resistance – translated, this means the body doesn’t bounce around as much as before. Ride comfort, too, is said to be better, despite the addition of the biggest tires that Acura has ever offered on any of its models at P255/55R18.
To meet the goal of exceeding German handling, the MDX Sport gets an active damping suspension that continuously controls roll and pitch, reduces squat and dive, and responds quickly to changing road and driving conditions while still providing what Acura engineers call a “magic carpet ride.” Delphi, the former General Motors supplier that is operating under bankruptcy protection, supplies the Acura MDX’s magnetic fluid shock absorbers, which are similar to those used for GM’s Magneride suspension. Acura swears up and down that it specifically tunes these shocks for use in the MDX, and that the result is different from what GM plops into a Buick Lucerne. What makes Acura’s active dampers worth the extra cost is that a Comfort switch allows the MDX Sport to provide a cushier, Lexus-like ride when desired but in Sport mode, the default setting for the system, Acura says the MDX exceeds the Porsche Cayenne’s handling capability.
Acura has the Porsche in its sights when it comes to braking, too. The 2007 MDX gets the biggest brakes ever offered on an Acura, 13-inch vented rotors up front and 13.2-inch solid discs in back. ABS, EBD, and Brake Assist are included as part of the system, as is Acura’s Cooperative VSA (C-VSA) stability control system. C-VSA can recognize when the MDX is on a slippery surface and automatically engages the SH-AWD to reduce the need for braking while maximizing grip. This sophisticated stability control system also includes trailer stability assist, which automatically retards trailer oscillation when towing.