The new Dodge Durango and Chrysler Aspen Hemi hybrids will share technology and basic transmission pieces with the hybrid GM SUVs, BMW X6, Mercedes-Benz M-Class, the next Ram, and potentially the Dakota. The main benefit is urban fuel economy with EPA at 19/20 mpg; over a mellow 145-mile ride ideal for economy and doing our best feather-footing, according to our on-board trip computer, we bettered those city and highway numbers.

With big utility hybrids like these, the term "no compromises" is tossed around with reckless abandon. Of course, there are compromises, primarily a lower tow rating (4700 pounds with the truck fully loaded) and an additional $3600 premium over a similarly equipped gas model. And some buyers may have a problem with no middle-row bucket seat option, no 2WD or low-range 4WD versions, a lux trim only, and less do-it-yourself serviceability. However, Chrysler claims the estimated tax credit of $1800 and a roughly $8000 advantage over the Tahoe hybrid.

The Hemi is a 345-horsepower, 380-pound-foot version of the 2009 V-8 with cam-in-cam variable timing but without the two-tract intake. It's mated to the two-mode transmission, which contains a pair of AC synchronous 65-kilowatt (87-horsepower/235 pound-feet) electric motors, but total system power output is kept to 385 and 380 (340 pound-feet available from 2000 rpm). A 152-pound NiMH 300-volt battery pack resides under the center-row seat, and it's all run by processing power (equivalent to three Mac G4s) that also tells the Hemi controller what it wants. The four fixed-ratio gears are used because they can't be beaten for power transmission efficiency in certain heavy-load situations.

Other changes include a separate cooling circuit, 25-watt pump and heat exchanger for the inverter/controller, an electric fan for the radiator stack, 4.5-kW motor to drive the air-conditioner's compressor, and a cabin humidity sensor below the rearview mirror to minimize compressor cycle time. The steering system from TRW is used on many European vehicles, employing a 1.5-kW motor to drive the pump feeding the standard hydraulic rack.

With added regen braking and no change to GVWR, the braking system wasn't upgraded--just adapted to electronic control. Fuel capacity remains 27 gallons in a reconfigured tank, the existing 18-inch tires were good for rolling resistance, and no spoilers or light body panels have been added.

Inside, a power gauge replaces the tachometer, "ready" and wrench/lightning bolt "high voltage service" lights have been added, and the nav screen offers system function/battery condition on a simple graphic to minimize distraction. When the Hemi's in MDS four-cylinder mode, the engine on the screen is color-split in half and the overhead mpg readout displays a fuel-saving mode.

Unless the battery is drawn down, the truck starts in electric mode. While you can get the hybrid up to 28 mph on electric power alone, the gas engine usually joins in at about 10 mph. Once it does, it often changes revs of its own accord, providing a bit of that CVT boat-reaching-planing-speed sensation. Mash it and the Hemi howl begins, and rolling to a stop yields an electric-motor/planetary gear whine supercharger fans will enjoy. If you focus on it, you can discern the transition between electric only and hybrid drive, but we suspect most owners won't notice, especially if they have the radio on and aren't watching any instruments or displays. Heavy braking, steering, and handling feel the same as a regular model with two passengers on board.

Engaging the tow/haul mode always starts the gas engine, but doesn't defeat electric-only operation...call it the powertrain planning ahead. There is every indication it would pull max load just as you'd expect from 385 horsepower and 380 pound-feet, and the gas you save getting there can be poured in the boat tank. With enough speed on and trailer surge brakes tuned to typical operation, going into regen mode--either by tapping the brake pedal or downshifting--will often trigger the surge brakes: Make sure you tune them carefully so they don't take over the retarding, robbing you of battery-pack recharging.

Of all the reasons Chrysler cited for needing a big SUV--and noting it's a "growing market"--we heard none mentioned in the Aspen owner demographic, only that of the Durango. However, even if the Aspen does go away as redundant, it didn't cost anything to include it in the program and expose a second brand to the hybrid hype.

Both run in the mid-$45,000 range--the Aspen apparently has $230 more in chrome, wood grain plastic, and boat-hull hood stamping costs--there are just a few options available: moonroof, DVD entertainment, trailer-tow package with four- and seven-pin connectors at the tongue, and perhaps a few shades of metallic paint. The blue "HYBRID Two-Mode Hemi" badge implies two-mode applies to the Hemi and begs the question, "What color badge would a BlueTEC diesel get?"

Two-Thirds Towing
Relative to a 4WD Hemi's 8700-pound limit, the hybrid versions give up about 2700 pounds in towing capacity. An apples-to-apples comparison can't be done, because the top Hemi rating applies with an optional 3.92:1 axle ratio (7200 pounds with standard 3.55:1) and the hybrid comes solely with 3.21:1 gears. However, since the upgraded axle is cheap, the Gross Combined is 2300 higher, and the base truck is almost 400 pounds lighter, it's clearly superior for towing anything more than moderate trailers on crowded routes.

Although GM's Tahoe hybrid ratings are similar, Chrysler folks told us this pair is rated at 6000 pounds because all reverse propulsion is electric (the "low" electric motor runs backwards)--the Hemi may be running to charge the battery, consume fuel vapors, or generate heat, but the motor does all the work. Since bad things can happen when an electric motor "stalls" and ancillary systems and controllers might overheat if overworked, grade testing in reverse yielded the 11,700 GCWR and simple math gives the 6000-pound rating.



2009 Chrysler Aspen/Dodge Durango Hybrid
GENERAL
Location of final assembly Newark, Delaware
Body style 4-door, 8-pass SUV
EPA size class Special purpose
Drivetrain layout Front engine, AWD
Airbags Front, front side, side curtain
POWERTRAIN
Engine type 90° V-8, iron block/alum heads
Bore x stroke, in 3.92 x 3.58
Displacement, ci/L 346/5.7
Compression ratio 10.5:1
Valve gear OHV, 2 valves/cyl, VVT
Fuel induction MDS SFI
SAE horsepower, hp @ rpm 345 @ 5300
SAE torque, lb-ft @ rpm 380 @ 4200
Transmission type Two-mode auto
Elec-variable low Infinite to 1.7:1
1st fixed 3.69:1
2nd fixed 1.71:1
3rd fixed 1.00:1
4th fixed 0.74:1
Elec-variable high 1.7:1 to <0.74:1
Reverse Infinite to 1.7:1
Axle ratio 3.21:1
Final drive ratio 2.37:1
Transfer-case model MP3010 1-speed
Recommended fuel Regular unleaded
DIMENSIONS/CAPACITIES
Wheelbase, in 119.2
Length, in 202.1
Width, in 76
Height, in 73.6
Track, f/r, in 64.4/64.5
Headroom, f/m/r, in 40.8/39.3/39.2
Legroom, f/m/r, in 41.4/37.4/34.5
Shoulder room, f/m/r, in 59.6/59.6/58.9
Cargo vol beh 1st/2nd/3rd row, cu ft 102.4/68.4/20.1
Ground clearance, in 6.9
Approach/departure angle, deg 23.7/27.6
Load lift height, in 33.6
Base curb weight, lb 5553
Weight distribution, f/r, % 55.3/44.7
Max payload capacity, lb 1497
GVWR, lb 7050
GCWR, lb 11,700
Max towing capacity, lb 6000
Fuel capacity, gal 27
CHASSIS
Construction Ladder frame
Suspension, f/r Independent, double A-arm, torsion bar, anti-roll bar/solid axle, coil/link, Watt's linkage, anti-roll bar
Steering type Rack-and-pinion
Ratio 13.2-18.9:1
Turns, lock to lock 3.4
Turning circle, ft 39.9
Brakes, f/r 13.2-in vented disc/13.8-in vented disc, ABS
Wheels 18x8.0-in alloy
Tires 265/60R18 Goodyear Wrangler SR-A
Load/speed rating 109/T
PERFORMANCE
EPA fuel economy, city/hwy, mpg 19/20
CO2 emissions, lb/mile 1
PRICE
Base price $45,570/$45,340
Options $2,705
Price as tested $48,045 (Durango)

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