The 2015 Renegade is the first Jeep to be imported into North America, but the Italian-built B-segment SUV represents a domestic engineering and design execution. Yes, its platform, transverse powertrain, and off-road systems and controls were developed here and tested on the same trails—including a section of the Rubicon, of course—as models that emerge from American plants. It comfortably demonstrated those capabilities in a Jeep Jamboree-developed off-road course we drove in northern California.
The volume powertrain choice is the Chrysler MultiAir 2.4-L four rated at 180 hp (134 kW) and 175 lb·ft (237 N·m) and paired with the nine-speed automatic introduced in the Cherokee. However, because the Renegade, at 3187-3572 lb (1446-1620 kg) is about 600 lb (272 kg) lighter, the calibration is specific, explained Arthur Anderson, Vehicle Line Executive. A Fiat engine, the 1.4-L MultiAir turbo four, is the base powerplant, but that's only offered with a six-speed manual. Both engine offerings are FCA (Fiat-Chrysler Automobiles) carry-overs.
New platform, highly-rigid structure
The Renegade platform is new, unrelated to the Fiat 500L, and will be shared with the forthcoming Fiat 500X crossover. Wheelbase is 101.2 in (2570 mm), overall length is 166.6 in (4232 mm), and the EPA interior volume is 118.6 ft³ (3360 L).
The boxy look notwithstanding, Cd is 0.35 on the 4x2, 0.36 on 4x4, and 0.37 on Trailhawk, the edition developed for serious off-roading. The vehicle has a rigid body-chassis, with 70% of its structure made of various grades of high-strength steel. FCA now provides only body-in-white bending numbers in Hertz, and the Renegade figure is 40 Hz. The torsional rigidity specification is static,1600 N·m/rad. Tow capacity with the 2.4-L is 2000 lb (910 kg).
The front structure includes a driver-side design to enable the Renegade to pass the narrow barrier offset test of the Insurance Institute for Highway Safety (IIHS), one requirement for an IIHS Top Safety Pick (TSP) rating. In addition to the conventional bracketry to distribute crash loads to the reinforced side floor rail and roof rail structure, the front of the floor rail is designed to direct crash energy to the engine, to push the car off the barrier, explained Anderson.
The Renegade also offers forward collision warning (FCW), a radar- and camera-based system. Adaptive cruise control isn't available, but there is brake assist and if the driver doesn't brake hard enough, the system can perform automatic braking from under 30 km/h (18 mph) down to 7 km/h (4 mph).
With the FCW package, Anderson said the vehicle will be proposed for a TSP+ label, IIHS top score. In addition, Renegade will offer such other electronic safety features as blind-spot identification and lane departure/control, as well as rear cross-path detection and park assist from a system with a rear camera and ultrasonic sensors.
There are three models in addition to Trailhawk in the line: base Sport, Latitude and Limited. Those three are standard-equipped with transverse front-wheel drive. Optional is Selec-Terrain Active Drive (all-wheel-drive variant with a 4WD Lock button to lock the front-drive PTU (power transfer unit) to the rear differential for off-road.
The fully independent suspension for front-wheel drive and four-wheel drive are similar: MacPherson struts in front and Chapman struts (basically non-steering MacPhersons) with lateral links, trailing arms, and lower control arms in the rear. The FWD front lower control arms are made of a single sheet of high-strength steel, the 4WD of two sheets.
4WD systems with Selec-Terrain
The terrain selection is biased to Auto (AWD), but also has choices for snow, mud, and sand. Snow may launch in second gear to minimize wheelspin, and includes engine, transmission, and traction control changes to reduce oversteer and improve traction. Mud allows a bit of additional wheel slip to help remove mud from tire treads. Sand uses traction control and a specific throttle map to control wheelspin.
This single-speed PTU is an electronically controlled, fully disconnecting design using an electric motor to operate a dog clutch. In Auto mode and light-load cruising, in effect it provides a FWD mode for maximum fuel economy—projected to be over 30 mpg EPA highway, and in Automotive Engineering's test delivered 30.3 mpg.
The rear differential has an electric-motor-operated multi-disc wet clutch, to separate the differential side gears (and therefore the axle shafts) from the carrier. So with the differential clutch open, rear wheels virtually free-wheel. With the PTU dog clutch disengaged, the two-piece propshaft also does not turn, so there is no fuel economy penalty with the 4WD system on Sport, Latitude, and Limited. However, the vehicle is always in Auto mode, and the system responds to wheelspin (as detected by the anti-lock brake sensors) within 500 milliseconds, explained Anderson. When the dog clutch in front and rear differential clutch engage, power is appropriately distributed to all four wheels.
Trailhawk is a complete package with front and middle underbody aero/skid plates, and underbody approach, breakover, and departure angl es are much higher than the other 4WD models. Its 4WD system adds hill descent control and manual Low, which with a 4.33 axle, vs. 3.73 on the other 4WD, provides a 20:1 crawl ratio for off-roading. The front system is always engaged. Like the other models when 4WD isn't needed, the rear differential wet clutch disengages to improve fuel economy. The drivetrain also has a 4WD lock selection.
With the Trailhawk system shifted into Low, Selec-Terrain control software enables a Rock position for climbing over rocky areas. In addition to the 20:1 crawl ratio, the traction control is more aggressive. If a wheel lifts, the ABS slows it to the same speed as the wheel with traction.
Trailhawk ride height is 8.7 in (221 mm), which is 0.8 in (20 mm) higher than the other models. The approach angle is 30.5º (vs. 24º on the other 4x4 models), breakover is 25.7º (vs. 24º), and departure is 34.3º (vs. 32.1º). The only physical difference, which accounts for the greater approach angle, is in the front end of Trailhawk vs. the others. The Trailhawk's greater ride height creates its advantages in breakover and departure angles.
New electronic architecture
The 4WD system's PTU dog clutch and rear differential electric clutch are controlled by the Drivetrain Control Module (DTCM) based on signals from the Controller Area Network (CAN) high-speed bus, one of two high-speed CANs (500 kb/s).
The CANs are part of an all-new electronic architecture called Atlantis, which, at this stage anyway, will co-exist with PowerNet, the Chrysler architecture introduced in 2011. Atlantis has three CANs, two high-speed and one medium-speed (125 kb/s) units. All three buses use the body control module as the gateway. The Atlantis body computer is the brain of the system, also holding vehicle configuration data, and operating the lighting, locking, and anti-theft systems among its numerous assignments.
One high-speed CAN primarily is for powertrain, the anti-lock brakes, and occupant restraint control (air bags, seat belts). It's wired to the OBD II connector and daisy-chained to the instrument panel and entertainment systems modules. The second high-speed CAN is for chassis and safety systems and is daisy-chained through the body computer and electric power steering module.
The medium-speed CAN (125 kb/s) is for entertainment and comfort functions.
Its name notwithstanding, the roof-mounted Radio Frequency Hub is not part of the entertainment system, but is on a high-speed CAN bus, where it monitors RF signals for passive entry and anti-theft and does tire pressure monitoring.
In addition, Atlantis has four LIN (Local Interconnect Network) buses, one of which is for communication between the Selec-Terrain panel on the control stack and the body computer.
Renegade also will be made in Brazil and China. Although the 1.4-L turbo and 2.4-L engines are the only ones available in the U.S. market, there will be a 1.6-L gasoline, 1.6-L turbodiesel, and two 2.0-L turbodiesels for other markets.Continue reading »