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All-Wheel Drive for Charger Pursuit

Written by Police Fleet Manager Staff

www.fleet.chrysler.com

 

"An AWD sedan that still remembers it is a RWD sedan"

 

 

All-Wheel Drive for Charger Pursuit

By Police Fleet Manager Staff

 

For mid-year 2014, the Dodge Charger Pursuit will be available with All-Wheel Drive. The Charger Pursuit will have the AWD option only with the 5.7L V8 engine.

There are no plans for an AWD option for the 3.6L V6 version of the Charger Pursuit. Both retail and police versions of the Charger 5.7L AWD use the 5-speed transmission. This trans has a long and successful track record in law enforcement use. The retail version of the Charger AWD with the 3.6L V6 uses an 8-speed, a transmission relatively unproven in police use. Perhaps there will be an AWD with the V6 / 8-speed drivetrain in a few years.

To get some initial driving impressions, we spent a lot of time in a Charger R/T AWD. This is the same Charger R/T AWD that has been making the rounds among some Midwestern police departments like the Michigan State Police and the Detroit Police. Unlike some car reviews, our driving impressions are not based on an afternoon media drive: we put 1,200 miles on the Charger R/T AWD over a period of two weeks.

 

Front Axle Disconnect

The Charger AWD driveline uses an active transfer case and a front axle disconnect system. The original retail Charger AWD (2007-2008) used an AWD system based on the Mercedes Benz 4MATIC system. This AWD system was fully engaged all the time. It was fixed to deliver 60 percent of the power to the rear wheels and 40 percent to the front wheels. Remember, at that time, Chrysler and Mercedes were the same company, DaimlerChrysler. Remember that the Dodge Charger and the Chrysler 300 are essentially an American version of the Mercedes E-class.

In 2009, the Charger AWD adopted a torque-on-demand system made by Borg Warner. In this system, the front wheels are disconnected from the engine-transmission until extra traction is required. This is essentially the same AWD system used on the Cadillac CTS4. Disconnecting the front wheels until more traction is needed or until conditions call for AWD results in a slight increase in fuel economy and slight decrease in driveline wear since the forward driveshaft and front half shafts are not engaged until needed.

 

Rear Wheel Dominant

When the AWD system is engaged, the power is split 38 percent to the front and 62 percent to the rear. That way, the Charger AWD always has the handling and the feel of a true RWD sedan, even when the AWD is engaged.

This driving experience is further reinforced by the Charger AWD defaulting to RWD and staying in RWD for just a second or two under tire slip during aggressive driving or adverse road conditions. A stab to the throttle affects the rear wheels for just an instant before all of the wheels divide up the torque.       

The Charger AWD automatically and seamlessly transitions between RWD and AWD. You simply cannot feel the front half shafts engage or disengage even if you are closely watching the display in the driver information center. The driver does not have to “do” anything. On the other hand, the driver can intentionally engage the AWD system a number of ways.

 

Six Systems Monitored

To determine when to engage the AWD, the Charger constantly monitors six systems or conditions: 1) stability control activation, 2) stability control switch, 3) windshield wipers, 4) AutoStick, 5) transmission shifter position, and 6) ambient temperature. The AWD automatically engages at temperatures below 37 deg F.

Turning the Traction Control – Stability Control OFF and turning the windshield wipers ON are two manual but awkward ways to activate AWD. A more sensible way is to simply engage AutoStick.

When AWD is automatically engaged by a loss of traction, it goes from RWD to AWD in about one second. However, when demand is activated, it stays in AWD mode for about five minutes even if no other traction problems occur. The logic is that if you have had one traction problem calling for AWD, you may have another one soon. So AWD stays engaged until it thinks the non-demanding driving is over. During a bit of traffic enforcement-oriented grassy median crossing, the AWD remained engaged for about an hour—until we stopped jumping the medians.  

A display in the driver information center clearly shows when the Charger AWD is in RWD mode or AWD mode. You can see exactly when the AWD activates and how long it remains activated. For example, AWD engages about two seconds after Traction Control – Stability Control is manually turned off. The Charger remains in AWD mode for about five seconds after Traction Control – Stability Control is turned back on. With the windshield wipers, AWD engages about five seconds after the wipers are turned on and remains engaged for about five minutes after the wipers are turned off.

 

Only When Needed

Unlike some AWD systems, the Charger’s AWD system does not engage and disengage multiple times per minute as conditions change. The Charger AWD remains a RWD as much of the time as permitted by traction. It doesn’t try to read your mind. It engages when needed, stays engaged only as long as needed, and then disengages. It doesn’t anticipate the need for traction during acceleration; instead, it waits for the amount of slip to demand the AWD engagement.

Also unlike other AWD systems, the Charger’s AWD system doesn’t send all of the power to just one axle and it certainly doesn’t send it to just one wheel. The front wheels assist the rear wheels—they never take over from the rear wheels.

The Charger AWD always remembers it is a RWD sedan. By sending most of the power to the rear wheels, under the most adverse conditions, the front wheels don’t get overloaded by the twin tasks of steering and propelling. That is the advantage of a RWD-based AWD system.

 

From Snow to Grass

Just how good is the AWD system on the Charger AWD? The Charger 5.7L V8 hits 60 mph in 6.0 seconds. With the same 5.7L V8, the Charger AWD hits 60 mph in 7.7 seconds…on GRASS…and using retail-oriented, all-season tires. Some of us have made a career of median crossing traffic enforcement. Some of us have the tow truck bills to prove it. The Charger AWD is a dream come true.

AWD is not just for snow-covered roads, and not just for rain-soaked roads, and sand, gravel and grass. AWD also has solid, proven advantages on dry pavement. In preliminary developmental testing, the Charger Pursuit AWD was two seconds faster than the Charger Pursuit RWD around the Grattan Raceway road course. AWD allows more of the horsepower and torque of the 5.7L HEMI V8 to be put to use…you get to use more throttle and you get to use it sooner.

 

Turning Diameter

The 38.7-foot turning diameter, curb to curb, for the Charger AWD is virtually identical to the Taurus-based Ford Police Interceptor Sedan and Chevrolet Impala 9C1. And all these police sedans turn a full 2 feet tighter than the outgoing Ford CVPI. Comments or concerns about the turning diameter of the Charger with AWD are simply unfounded, based on misinformation or lack of driving experience.

From tight U-turns in an urban setting to rapid U-turns in a rural setting, it is impossible to tell any difference between the Charger RWD and Charger AWD, or among any of the NextGen sedans, while the better maneuverability than the old CVPI is obvious to all.

The exact ride height of the police package Charger Pursuit AWD is still under development. However, the ride height (ground clearance) of the retail Charger R/T AWD and Charger R/T RWD are virtually identical. Since increasing the ride height affects high-speed handling, don’t expect the ride height on the Charger Pursuit AWD to be much, if any, different from the standard Charger Pursuit. Like the Ford Police Interceptor Sedan, the police version of the AWD sedan only gives you better traction, not more ground clearance.

 

NVH in Mobile Office

In the mobile office for 8–12 hours a day, Noise, Vibration & Harshness really matter. The Charger AWD does not have any of the driveline vibration coming through the steering wheel as felt in some FWD and AWD vehicles. Why? The Charger AWD operates in RWD mode unless conditions specifically call for AWD to engage the front wheels.

What that happens, there is obviously so much more going on in the driving experience that any driveline feedback through the steering wheel is simply not noticed. The Charger AWD drives and feels like a RWD sedan until road conditions deteriorate or driving becomes very aggressive.

The Charger AWD has the performance handling and driving dynamics of a true RWD sedan, and then only when needed, it has the all-weather traction of an AWD sedan.


Published in Police Fleet Manager, Sep/Oct 2013

Rating : Not Yet Rated


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