Acura MDX
OVERVIEW
The 2001 Acura MDX(TM) was launched in 2000 to define a new era in the evolution of luxury sport utility vehicles, treading beyond the limits of existing SUVs in terms of handling, packaging efficiency and environmental impact. It was developed with the overriding goal of setting new benchmarks for luxury SUV performance. That performance goal applies to the three main themes of the development concept; to establish new performance benchmarks in the SUV category for versatility, responsibility and dynamic performance. As the development process progressed, an additional development goal was added - furnishing the vehicle with an array of cutting edge features that effectively "defeat winter" for its driver and passengers - limiting the harsh effects of the cold winter months on MDX occupants.
After a stellar first year, in which the MDX established itself as the #1 SUV by capturing both the Motor Trend Sport Utility of the Year and the North American Truck of the Year awards, Acura set out to make it even better, increasing its already formidable performance and further refining the MDX inside and out. For 2003, a new engine boosted horsepower from 240 to 260, a new 5-speed automatic transmission was added and the chassis and suspension were enhanced to take advantage of the additional power. A new drive-by-wire throttle system was included and the state-of-the art VTM-4(R) four-wheel drive system was revised to provide enhanced vehicle control during acceleration, cornering and braking.
The 2004 model year MDX received exterior styling enhancements that gave ita muscular, performance-oriented look representative of its impressive powertrain. For 2005, Acura turns its attention to updating the MDX interior with the latest technologies and enhanced safety. To that end, XM(R) Satellite Radio is now standard on all models. The optional Acura Navigation System with Voice Recognition(TM) has been enhanced to provide a quicker response time, additional voice recognition commands, more points of interest and access to the ZAGAT restaurant guide. MDX models equipped with the navigation system will also receive the OnStar system. In addition, the HandsFreeLink(TM) wireless phone interface, which allows hands-free dialing to restaurants and other points of interest, is now included in the Touring Package. Models equipped with the optional Rear Entertainment System also come equipped with a 6 disc, in-dash CD player, compared to an underseat6 disk player on the 2004 model.
Chassis enhancements for 2005 include an improved Vehicle Stability Assist (VSA(R)) system and Brake Assist, which helps drivers apply full braking pressure in an accident avoidance situation.. Three new exterior colors are added: Desert Rock Metallic, Billet Silver metallic and Steel Blue Metallic. A larger, redesigned gas tank, increases capacity by over one gallon, and extends driving range while at the same time helping the MDX meet LEV-2 Evaporative emissions requirements.
For 2005, significant changes to the MDX include:
* Standard XM Satellite Radio
* Acura HandsFreeLink Bluetooth wireless phone interface included in optional Touring Package
* OnStar on all models equipped with navigation system
* Larger fuel tank
* In-Dash 6 Disc CD player on models equipped with Rear Entertainment System
* Enhanced Vehicle Stability Assist (VSA) system
* Enhanced navigation system
o Quicker response time
o Additional voice recognition commands
o More points of interest
o ZAGAT Guide
* LEV-2 ULEV emissions system
* 3 new exterior colors including Desert Rock Metallic, Billet Silver Metallic and Steel Blue Metallic
PERFORMANCE ATTRIBUTES OVERVIEW
Outstanding performance has always been a fundamental Acura character trait. The development of Acura's first in-house designed and engineered SUV presented the opportunity for the engineers to sidestep the shortcomings of products already on the market and begin with a fresh approach to the SUV equation. That approach was to create the first no-compromise SUV - melding attractive design, unmatched versatility, driving exhilaration, social responsibility, and value in one neatly wrapped package.
The MDX is powered by a 3.5-liter, V-6 engine, tuned to deliver an outstanding 265 peak horsepower at 5800 rpm and 253 lbs-ft of torque between 3500 and 5000 rpm. Providing V-8-like power, this engine is coupled to a compact 5-speed automatic transmission and a drive-by-wire throttle system (DBW) that deliver precise shifts and reduced shift shock. The MDX's standard VTM-4 four-wheel drive system works seamlessly with the DBW and the standard Vehicle Stability Assist (VSA) system to enhance performance on low traction surfaces, and enhance stability in all conditions.
The MDX's 4500-pound boat towing package (3500-pound for trailers) was achieved by tuning the powertrain and chassis systems to manage heavy loads with confidence. This vehicle's wider-than-normal stance, high-torque engine, wide-ratio 5-speed automatic transmission, and powerful brakes yield a highly competent tow vehicle.
ACCELERATION, BRAKING, CORNERING PERFORMANCE
A pillar of the Acura development approach is that the driver's seat should be the most rewarding seat in the vehicle. With this in mind, the development team groomed the MDX to behave like a sports sedan when driven in an assertive manner. The starting point is a 3.5-liter SOHC V-6 engine that combines a remarkably broad range of torque - 253 lbs-ft between 3500 and 5000 rpm - witha potent 265 horsepower at 5800 rpm. Factor in a wide-ratio, 5-speed automatic transmission and a sensible curb weight achieved by the shrewd use of high-strength materials, and MDX posts outstanding acceleration performance.
Acknowledging that ordinary SUVs feel clumsy and cumbersome, extra effort was invested in making sure that the MDX provides driving exhilaration consistent with Acura standards. Chassis systems and the power-to-weight ratio are optimized for all-around performance.
The 2005 MDX features 4-channel Vehicle Stability Assist (VSA) that has been enhanced with active yaw control for increased driver control during accident avoidance maneuvers, aggressive cornering and inclement weather. The VSA system monitors lateral (cornering) stability and seamlessly integrates traction control, 4-wheel drive, Anti-lock braking, throttle control and stability control functions.
Demanding drivers expect a vehicle's braking system to match its acceleration- and MDX measures up to that task as well. To provide short stopping distances, high fade resistance, and a reassuring pedal feel, the MDX's four-wheel disc braking system uses large-diameter rotors, extra-rigid calipers and dual-piston front calipers. The 4-channel Anti-lock Braking System (ABS) features electronic distribution of brake forces for optimum use of the traction available at each corner of the vehicle, and new for 2005, Brake Assist. The result is responsive braking performance for short stopping distances with a confident pedal feel.
Excellent handling begins with getting the fundamentals of vehicle dynamics right from the start. A wide track maximizes stability and cornering grip, so MDX has the widest track in its class. The MDX design was tuned to achieve the best possible maneuverability and helps to minimize the cumbersome feeling that plagues most truck-based SUVs.
To overcome the usual ride-versus-handling compromises, engineers incorporated front and rear subframes to isolate road noise and driveline vibration from the passenger compartment, along with independent front and rear suspension systems with extra wheel travel and fine-tuned suspension geometry. Low roll centers combined with large stabilizer bars provide progressive, predictable cornering response and excellent stability at the limit of adhesion. Lightweight
materials - such as aluminum castings for all major driveline components and extensive use of high strength steel unit body components - give MDX an overall agile feeling.
THE VERSATILE SUV
The theme of versatility was applied to each area of development, from exterior and interior styling to powertrain to chassis design and the many performance targets. From the inside out, MDX offers many options to the driver and passengers including the potential for six seating configurations from the split and folding second and third-row seats.
The options don't end there however, as the powertrain is tuned for optimum performance in virtually any condition the driver is likely to encounter. Key to this is an engine that is powerful, fuel efficient and low in emissions - with a broad range of torque and horsepower. Likewise, the 5-speed transmission offers one of the widest overall gear ratio ranges in the segment, ensuring that engine speeds are matched as closely as possible to the demands of the driving conditions at any time.
MDX's unit body construction provides the optimum balance of strength and rigidity while still being the most space and weight efficient construction for an SUV of this size. All suspension, steering and braking components are designed to minimize unsprung weight to improve handling precision, but are still rugged enough for medium-duty, off-road driving. For 2005, structural enhancements were made to allow all MDX models to further enhance safety.
THE RESPONSIBLE SUV
MDX demonstrates a high degree of environmental responsibility by providing excellent fuel economy with very low exhaust emissions. Thanks in part to a high output exhaust system, and innovative fuel injectors, the MDX meets stringent LEV-2 ULEV emissions levels. Changes to the shape of the gas tank increase capacity and reduce sloshing noise while also helping the MDX meet LEV-2 Evaporative standards. The MDX's combination of 17 mpg city and 23 mpg highway places it ahead of many competitive luxury SUVs in fuel economy and proves that powerful SUVs can be environmentally responsible and fuel efficient.
Safety has been an integral part of the MDX design from its inception, and an important aspect of the responsible SUV concept. To help avoid situations that could lead to a collision, MDX is engineered with the agility and maneuverability necessary to help maintain control in emergency maneuvers.
When a collision is unavoidable, MDX helps protect its occupants with a reinforced body structure and state-of-the-art occupant protection features. The MDX features front dual-stage, dual-threshold airbags, driver and front passenger side airbags and a Side Curtain Airbag system to help protect vehicle occupants from head and neck injuries in the event of a sufficient side impact. A Tire Pressure Monitoring System uses sensors in the wheels to alert the driver when tire pressure drops below 25 percent of the recommended level.
MEDIUM-DUTY OFF-ROAD CAPABILITY
The engineers who designed the MDX tested a range of competitive SUVs to help quantify off-pavement use patterns, customer needs, and engineering targets for the MDX. Accommodating extreme off-road use can impose compromises elsewhere in the vehicle, such as added weight, awkward entry and egress, poor fuel economy, and reduced on-road performance. With this in mind, the MDX team visited nine off-road parks in California, Nevada, Kentucky, North Carolina, and Michigan to study SUVs in their natural, off-road habitat. While a few competitors offer the extra ground clearance, driveline equipment, and chassis hardware necessary to support ambitious off road excursions, the engineers learned that few customers use these extreme capabilities regularly.
After observing casual off-roaders, MDX engineers concluded that surpassing the class's most capable off-road machine was not in MDX's best interests and that a medium-duty off-road capability was most consistent with the philosophy embraced by the MDX. Medium-duty capability would readily support trips into the wilderness for camping or to launch a boat without providing the rigorous equipment needed to conquer the extremes of the Rubicon Trail.
To define exactly what constitutes medium-duty off-road capability, the MDX engineering team selected 14 key performance criteria based on observations of casual off-road adventurers. They then constructed special test courses at their R&D facilities in North America to assure that MDX delivers all the intended capabilities with impeccable reliability and durability.
The list of test courses includes:
* 30-degree dirt hill
* Sand hill
* Water pit
* Rock roads
* Embedded log course
* Step-up, step-down
* Sand drag strip
* Gully course
* Ground contact course
* Washboard road
* Frame twister
* Power hop hill (23-degree slope with rippled surface)
* Gravel road
* Startable grade
Numerous engineering changes were based on experiences gained in testing. These included:
* A deeper oil pan was included to meet the hill climbing criteria.
* A more effective air filter was specified to remove dust from the engine's air supply.
* The tow hooks were upgraded to handle loads imposed during extraction from "stuck vehicle" situations.
* Waterproofing was added to support MDX's ability to traverse up to18-inch-deep bodies of water.
* Throttle actuation was calibrated to provide more sensitive control over engine output at low speeds.
For an acid test, engineers took prototype vehicles for a 200-mile off-road test on the Mojave Trail located in Southern California. This gauntlet of loose rocks, sandy washes, twisting grades, and narrow escarpments helped ensure that MDX has what it takes to venture off road and home again with confidence.
The results speak for themselves - MDX will climb a 31-degree (60-percent) paved slope with a two-passenger load. It has eight inches of ground clearance,a 28-degree approach angle, a 21-degree departure angle, and a 21-degree breakover angle for negotiating rough terrain. It can claw up a 28-degree (53-percent) dirt slope from a dead stop.
TOWING
One of the reasons people buy SUVs is to be able to haul pop-up campers, medium-sized boats, and recreational vehicle trailers. To understand this facet of the MDX's makeup, MDX engineers polled focus groups and studied survey results that tapped 200,000 households. Their findings offered the insights needed to properly outfit the MDX to surpass the towing expectations of most customers.
Ultimately, the engineers concluded that a casual or weekend towing capability was most appropriate for MDX. Customer feedback helped set the towing limit at 4500 pounds for boats and 3500 pounds for other types of trailers. A heavier load is acceptable with boats because their pointed bow shapes impose less aerodynamic drag on the towing vehicle than a slab-faced, square-cornered trailer. The 3500/4500-pound rating is calculated to include up to four passengers and their cargo.
VARIABLE TORQUE MANAGEMENT(R) 4-WHEEL DRIVE SYSTEM (VTM-4(R))
The MDX is equipped with an advanced 4-wheel drive system - VTM-4. The VTM-4 system consists of a pair of computer controlled wet clutches in the rear axle that work to maintain traction in all types of conditions.
Unlike other on-demand 4-wheel drive systems, MDX doesn't wait for slippage to occur before going to work. Instead, torque is proactively delivered to the rear wheels in proportion to forward acceleration to supplement front-wheel drive. This innovative, proactive approach pays two dividends: on dry pavement, there's less likelihood of torque steer (a tendency for propulsion forces to tug at the steering and nudge the vehicle off line) and there is more front tire adhesion available for cornering. In snow or wet conditions, automatic and proactive all-wheel drive gets the vehicle moving from a standstill with less chance of wheelspin.
If conditions are really slippery and wheel spin is unavoidable, VTM-4 instantly reacts by adding rear-wheel torque in proportion to both the slippage and the rate of increase of slippage. This enhances performance on low traction surfaces and also improves steering trace and feel during acceleration. In addition, the new VSA system further enhances traction in different conditions by providinga limited-slip differential effect for the front wheels.
A special lock mode is also provided to help extract the vehicle from a stuck condition. To use this get-out-of-a-snowbank capability, the driver moves the shift lever to first, second or reverse and presses the VTM-4 lock button on the dash. With the lock mode engaged, VTM-4 "locks" the rear axle to provide maximum power transfer to each rear wheel. As speed increases above six mph, the system automatically reduces the lock effect to the rear axle. By 18 mph, the system reverts to normal mode.
DEFEAT WINTER OBJECTIVE
While studying competitive vehicles and the SUV marketplace, the MDX development team discovered that a well-designed product could be an effective defense against some of the frustrating rituals of the coldest months of the year. Based on that insight, members of the MDX development team that had grown up in northern parts of the U.S. drew on their personal backgrounds to formulate a clever "defeat winter" objective for MDX - consisting of a long list of designed-in features and systems designed to provide superior cold-weather performance. The result is that MDX can be a major confidence builder for those faced with driving through severe winter road conditions.
The MDX's winter-beating tactics begin with a chassis engineered for excellent dynamics on wet, icy, or snowy pavement, the VTM-4 all-wheel-drive system and Vehicle Stability Assist (VSA). Various other chassis details are also engineered with a priority on winter driving. MDX's Goodyear and Michelin tires are compounded with silica to enhance ice and snow traction at cold temperatures. Testing has demonstrated that the grip of these tires is superior to many of the snow tires currently on the market. MDX's front suspension has a very low scrub radius so that braking on split-friction surfaces (such as when one side of the vehicle is on ice and the other side is on dry pavement) does not tend to pull the vehicle in one direction or the other.
Total roll stiffness is equitably distributed so that cornering response is linear and predictable even at low lateral Gs experienced during slippery conditions. The driveline is designed to provide natural and neutral handling response on snow and ice. With a static ground clearance of 8 inches, MDX is unlikely to get mired in snow drifts. The Anti-lock Braking System (ABS) is equipped with electronic brake-force distribution and four channels to provide maximum steering control even when traction varies dramatically from wheel to wheel. To preserve lateral stability, the rear brakes are programmed with a select-low strategy to modulate line pressure at both rear wheels as soon as either one approaches lock-up.
Features and amenities included as MDX standard equipment further enhance its winter-driving prowess. The rear heater is electronically linked to the operation of the front heater to speed warm up after a cold start and heat is ducted to all seating positions.
Electrically heated front seats and window defoggers are standard. Rear splash guards are provided to deflect slush and stones away from the side of the vehicle. Extra seals positioned at the bottom of the doors keep mud and slush from building up on lower surfaces that are likely to contact long coats, pant legs or dresses. Likewise, the windshield molding and the outside rearview mirror mounting trim are shaped to guide moisture flow away from the side windows for optimum foul-weather visibility. Door-mounted rearview mirrors are electrically heated to clear frost and fog.
MDX models equipped with the Touring Package are equipped with rain-sensing windshield wipers that, when in automatic mode, adjust wiper speed to correspond to the amount of rain that is contacting the windshield. The windshield washer reservoir is a large 1.2 gallons for a generous supply of washer fluid, and an indicator light advises the driver when it's time to replenish that fluid. Washer nozzles are engineered for optimum performance with a fluidic design in front and a jet-type sprayer in back. Since remote keyless entry is standard equipment on MDX, owners will not be kept from entering their vehicle by a frozen lock cylinder.
