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First Drive: NextGen Dodge Charger Pursuit

Written by PFM Staff

The newly engineered 2011 Dodge Charger has received far more changes than a restyled grille and new taillights. Everything above the rolling platform has been improved. The NextGen Charger keeps everything that is good about the 2006-2010 Charger. It holds fast to what has made it the most talked about, and most desired, police sedan in decades. At the same time, the 2011 Charger is greatly improved in the areas suggested by the Charger’s customer base, and that includes the police.

Big, Bad HEMI

During the past few years, Chrysler has made big changes and small tweaks to law enforcement’s most powerful engine, the 5.7L HEMI® V8. First, Chrysler added its Multiple Displacement System (MDS), which deactivates four cylinders under light throttle. Then, it widened the software parameters so the MDS kicks in sooner and remains in V4 mode longer. In the past, MDS required steady throttle at speeds under 45 mph to go into four-cylinder mode. Now, MDS will kick in under steady throttle at speeds up to 70 mph.

Second, for 2009, Chrysler upgraded the 5.7L HEMI to the Eagle version, which included Variable Valve Timing (VVT). This change boosted horsepower a little and torque a lot. So much so that the rear gear ratio was raised from 2.82:1 to 2.65:1 with no loss in performance. Yet the numerically lower gear ratio allows the engine to turn at lower rpms for the same vehicle speed, and that helps fuel economy. For 2011, a 3.06 ratio axle is optional on the Charger V8 for even faster acceleration.

Decel Fuel Shutoff

The HEMI in the 2011 Charger now uses another method to achieve better fuel economy in actual driving. Dodge calls it Interactive Deceleration Fuel Shut Off (iDFSO). With iDFSO, the engine controller shuts off the flow of fuel during vehicle deceleration. The fuel is shut off completely under two basic scenarios. The first scenario: lifting your foot off the gas pedal when the engine is running at higher rpms, for example, 3500 rpm. The fuel is cut to prevent high catalyst temperatures, and the fuel will resume as the rate drops to about 1200 rpm.

The second scenario is during a normal foot lift from a steady state where the transmission torque convertor is in slip control. The fuel is completely cut off after a short delay from closed pedal when the transmission is not shifting and the torque convertor is holding the engine rpm. The transmission will downshift with the fuel off as the vehicle speed decreases. The fuel turns back on as the rate approaches 950 rpm and/or the torque convertor unlocks.

In typical drive cycles, the fuel will be off about 5 to 8 percent of the time the vehicle is moving, with improvements to both fuel economy and brake pad life. The vehicle may feel like it is not “coasting” as far on deceleration as the previous models did because fuel is not being used to propel the vehicle at closed pedal.

As the pedal is lifted to coast to a stop on an MDS-equipped engine, the iDFSO (fuel shutoff) and the MDS (cylinder deactivation) work in combination with one another. The fuel will shut off or turn on in either MDS mode (8 cylinder or 4 cylinder). MDS may also activate during a fuel shutoff, but the activations will not happen at the same time. The vehicle deceleration will be milder while in 4-cylinder mode. Light pedal tip-ins will stay in 4-cylinder mode as the fuel is turned back on. When coasting to a stop, 8-cylinder mode is re-enabled after the fuel turns on.

Brand New Pentastar V6

The big news is that fuel economy is also up with the standard V6. The old-tech 3.5L V6 gave less than expected fuel economy. This engine, dating back to the early 1990s Dodge Intrepid, has finally been replaced. For 2011, the police Charger comes standard with the new 3.6L Pentastar (formerly Phoenix) V6.

This totally new, Variable Valve Timing engine was introduced on the 2011 Jeep Grand Cherokee. It was promptly recognized by Ward’s Automotive as one of the Ten Best Engines for 2011. The new 3.6L V6 produces more horsepower and torque than the old 3.5L V6. The 3.6L V6 has 285 hp, which is 35 hp more than the 3.5L V6.

Solving the number two complaint, fuel economy, the new 3.6L engine gives true V6 levels of economy. In an era of climbing gas prices and no-idle policies, it was a bit embarrassing when the 5.7L V8 got better mileage than the 3.5L V6. All of that has changed. The 3.6L V6 gets 19 mpg City (3 mpg/about 12 percent better) and 26 mpg Highway (1 mpg/about 8 percent better). This engine is also E85-capable (FlexFuel).

Dodge is as serious about this new V6 as Ford and Chevy are about their new V6s. This will be the corporate V6. By 2013, Chrysler will transition from seven different V6 engines (2.7L to 4.0L) to just one—this 3.6L Pentastar. The 3.6L V6 will also get MultiAir technology as a running change later in the 2011 model year or early in the 2012 model year. More on that major improvement to Variable Valve Timing technology in a future issue.

The 2011 Charger uses electrically assisted power steering. This is still fully mechanical steering, not electric steering like some hybrid vehicles. Only the power-assist part is electrical. An electric motor drives the power steering pump. This eliminates the weight, maintenance and engine drag of the power steering pump and hoses. Importantly, it also allows very easy and precise changes to the steering boost as speeds vary. Parking lot maneuvers: lots of boost. Traffic enforcement overtake speed: very little boost. The new steering has an even better on-center feel.

Better Handling...Really

No police officer or sheriff’s deputy complains about how the police Charger handles. Some may want the Electronic Stability Control to wait just a bit longer before kicking in. However, all of us are getting used to the NHTSA-mandated stability control. Instead, the directive to improve the handling of all Dodge-marque vehicles came from the top. The trend in the Dodge brand is away from brute muscle car and toward a better overall balance of road performance, thus the emphasis on seat comfort and drivability.

The 2011 Charger has the same overall size, weight and wheelbase as the older Chargers. It still uses the same 18-inch tire size. It has the same double A-arm front suspension and the same 5-link independent rear suspension. To improve handling, Dodge benchmarked perhaps the best handling sedan in the world, the Ultimate Driving Machine. What makes those BMW sedans handle so well? To find out, Dodge spent lots of time in a BMW 5-series.

The secret, as all road racers and oval track enthusiasts know, turned out to be initial negative camber in the front suspension. The Charger wheel alignment calls for nearly zero camber. That means when looking at the car from the front, the wheels and tires are perfectly straight up and down. Negative camber means the top of the tire tilts slightly in toward the car and the bottom of the tire tilts slightly out away from the car.

When making a turn, the suspension geometry of the older Charger immediately goes to positive camber from the initial zero camber. Positive camber lifts the inside of the tire contact patch (i.e., less tire grip). On the 2011 Charger, the initial negative camber goes from negative to zero camber and eventually to positive camber as the car is cornered harder. This keeps the tire patch in flatter contact with the road surface. The front tires have more grip, especially under acceleration as weight is shifted off the front contact patches toward the rear. The end result is less initial understeer and less total understeer. A little change…a big improvement.

A little negative camber goes a long way! Between 1/2 degree and 1 degree of negative camber makes the Charger a whole new car. The car feels lighter and more responsive. The initial turn-in is much more responsive, and the accident avoidance drill of turn-in, turn-back is much more nimble. If you are familiar with the older Chargers, the improvement in steering and handling is noticed on the very first turn at urban or highway speeds.

Dodge also reinforced the unibody structure near the rear axle mounting points. Dodge is a past-master at unibody structures. Unlike the competition recently forced into unibody platforms, every Chrysler product since 1957 has used some type of unibody. The subframe/cradle around the inner wheel well housing is a different and reinforced design. It is thicker and more rigid.

Strengthening this area reduces wheel op under heavy acceleration and heavy braking. The stiffer the body structure, the better the suspension can be tuned to do its job. Dodge found that beefing up this section made the rear suspension more rigidly mounted. That means the springs, shocks, sway bars and link bushings are much more predictable in their damping action. Also new for the 2011 Charger are mono-tube (Bilstein-style) shocks.

The Dodge Charger already has the best braking performance of any police vehicle. For 2011, the Charger will use the same calipers as the older Chargers. However, the new cars use heavier mass rotors. These rotors are backward compatible with older Chargers.

New Pursuit Tires

Also new for 2011 is a different OE pursuit tire. No one put Continental ContiProContact tires back on the police Charger anyhow. This Conti tire came in second overall in the Police Fleet Manager police tire performance tests, but their national tire pricing programs were intermittent and the distribution system was limited.

The 2011 police Charger will come with either the Firestone Firehawk GT Pursuit or the Goodyear Eagle RS-A. At this point, the Firehawk GT Pursuit, the tire so many Charger fleets are adopting, will be standard. The Goodyear Eagle RS-A will be a no-charge option.

This Firestone tire came in first overall in the Police Fleet Manager police tire tests. This Goodyear tire came in third behind the Firestone Firehawk and the Continental ContiProContact in the PFM tire tests. For more information on the tire tests from the July-August 2009 issue of PFM, go to www.hendonpub.com, click Resources and then click Article Archives.

SIDEBAR
BIG CHANGES AFTER MSP TESTS


The Michigan State Police test of the 2011 models was literally a test of pre-production vehicles (Dodge, Chevy) and prototype vehicles (Ford). All three automakers made big changes to their police vehicles between the mid-September MSP tests and the mid-November Los Angeles Sheriff tests.

For their part, Dodge powertrain techs broke out their laptops to find the missing performance from their brand new 3.6L V6. One of the biggest disappointments from the MSP tests—the acceleration of the Charger V6—became one of the brightest stars from the LASD tests.

The 3.6L, 24-valve DOHC Pentastar V6 was introduced on the redesigned 2011 Jeep Grand Cherokee. The redesigned Charger did not go into production until January 2011. To run the brand new car at the MSP tests, Dodge literally dropped a production Grand Cherokee engine into a pre-production Charger.

Quite simply, not enough time was available to fully tune the crossover V6 to the police sedan, and the result was lame performance at MSP. However, in the two months between major police tests, a great deal of effort and high-profile attention was spent on the Charger’s V6. The slam dunk at LASD is the proof.

The Charger V6 reached 60 mph in 8.7 seconds at MSP, and in 8.4 seconds at LASD—an improvement, but only a small one. It reached 100 mph in 23.9 seconds at MSP, and in 20.8 seconds at LASD—that is a huge change.

Heads up to fleet managers: The LASD numbers represent the production Charger. For the record, the new Charger V6 accelerates a lot faster than the Ford CVPI V8 and the Chevy Impala V6.

So, what changed? Rear gear ratio? Camshaft profile? High-stall torque converter? Larger inlet air valve? Less restrictive exhaust? Nope. It was just calibration changes, a computer flash, made to the engine and to the trans. Among the many changes were engine rev limits and trans shift points. Basically, the V6 powertrain calibration ­­was changed from being optimal for a 4,850-pound Grand Cherokee to being optimal for a 3,990-pound Charger. Specifically, the Charger V6 keeps the extreme economy 2.65 rear gear ratio.

Published in Police Fleet Manager, Jan/Feb 2011

Rating : 6.5


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