“Meeting 54.5 mpg will be a challenge, but we have a lot of customers who want to drive this,” said Brenna Kaufman, pointing towards the 2015 Dodge Challenger she unveiled to a group of media in Chrysler’s Tech Center Design Dome. Kaufman, the car’s Chief Engineer, smiled as she pondered the coupe’s Shaker cold-air induction scoop poking through the Sublime Green hood. The paint color is identical to the hue conceived during the era of Afros and bell-bottoms and used on the 1971 Challenger that is the new model’s inspiration.

“I hope muscle cars never go away,” Kaufman opined, “but we as a company have no choice but to prepare ourselves and continue to work on more efficient technologies and powertrains.”

That’s precisely what Chrysler has done to its latest E-segment L-platform cousins, the Challenger coupe (LA program) and Dodge Charger sedan (LD), officially launched at the 2014 New York International Auto Show. The classic American rear-drive models get significantly refreshed for MY2015, with all-new interiors. Charger is comprehensively reskinned. Major technology upgrades shared by both cars include Nexteer’s electric power steering that is worth a claimed 3% increase in fuel efficiency versus the previous hydraulic-based system.

The addition of EPS enabled the addition of DST—driver steering torque—an electronic steering-dynamics system that makes steering corrections and automatically controls oversteer on low-grip road surfaces in all driving conditions. The EPS also is fully integrated with the vehicles’ electronic stability control to help compensate in split-traction, torque-steer, and pull-drift (crowned road) situations, said Kaufman.

Also new are active-noise cancellation exhaust systems from Faurecia, which help the cylinder-deactivation-equipped V8s avoid the “four-banger” exhaust tone when they’re running in "deact" mode. The cars also get the ZF-licensed 845RE eight-speed planetary automatic transmissions across all V6 and V8 models, and new cast-aluminum, four-bolt rear axle housings, among other fairly minor mass-reduction actions.

Skin in the Charger game

Both Charger and Challenger retain primarily steel body structures, with aluminum hoods. Charger, which enjoyed the lion’s share of the 2015 program budget, received new exterior panels except its carryover roof panel and windshield. Charger’s body construction benefits from elegant laser-welding on the roof-to-bodyside joints, whereas Challenger (built in the same Brampton, Ontario, plant but processed on a different welding line) retains its less expensive ditch joint with plastic trim strip covering.

“I would have loved to have laser-welded roof on the Challenger,” said Kaufman. “It’s a huge investment, but it’s a beautiful thing on the car.”

Why the greater investment in the Charger? “Well there’s no mistaking the 2014 Challenger from the 1970 model, and it turns a lot of heads. So we had to be very careful there,” Kaufman explained. “The trick was to update it while maintaining its heritage. So our perfect recipe was to go from 2014 to 2015 by following the 1970 to ’71 transition, and putting our money into the interior.”

Automotive Engineering asked Kaufman, who also led development of the 2011 Charger prior to joining the LA program, why neither 2015 car appears to bring significant mass reduction. The cars’ base-model curb weights—Challenger SXT at 3834 lb (1735 kg) and Charger SE (RWD) at 3934 lb (1784 kg)—remain at rough parity with the outgoing models.

“From an engineering perspective, to do really significant mass reductions we’d need an all-new architecture,” she said. “For example, changing to an aluminum decklid, roof panel, and doors would net us some useful gains but it wouldn’t take us down a full weight class, which is 300 pounds. So we concentrated on bringing in the eight-speed, the EPS, and numerous other changes such as engineering new four-point rear cradle mounts (versus the 2014’s three-point mounts). And Nexteer was great to work with during development of the steering system, by the way!”

Dodge's new "Performance Pages" 

While the new Charger is able to squeeze 31-mpg highway fuel economy from its most efficient powertrain (3.6-L V6, eight-speed automatic, and 2.62:1 final drive ratio), the SE and SXT models equipped with all-wheel drive deliver 27 mpg highway. The AWD system features a segment-exclusive active transfer case and AAM-designed and supplied front axle-disconnect system to optimize efficiency.

The two modern muscle machines also receive numerous performance upgrades, with Chrysler spreading its Scat Pack “factory accessory” packages further into the nameplates. And these cars go hand-in-hand with Hemi V8 power, the 6.4-L Scat Pack Shaker models aimed at hardcore enthusiasts offering a projected 485 hp and 475 lb·ft (362 kW and 644 N·m, respectively—SAE ratings not finalized at time of publication), the Shaker cold-air induction systems being responsible for some of the gains. The unofficial numbers represent up to a 113 hp and 65 lb·ft (82 kW and 88 N·m) increase compared with the 5.7-L V8—gains of more than 30% in horsepower and 18% in torque.

The factory-accessory program has been extremely profitable for Chrysler and its Dodge dealers and is the reason why the Super Track Pak, which features nearly a catalog’s worth of performance chassis upgrades, has been made available on all 2015 Challengers, including 3.6-L V6 models for the first time. The Super Track Pak lowers the suspension by 0.5 in (12.7 mm) and adds specially calibrated Bilstein shock absorbers and upgraded brakes.

The Super Track Pak includes a shortcut button to the new Dodge Performance Pages embedded in the 8.4-in touch screen radio. The system provides visible performance information such as programmable shift light indicator, reaction time, 0-60-mph times, g-force indicator, and lap times in the 7-in TFT (thin-film transistor) customizable cluster display.

The cars' integrated electronic safety system is new for 2015. It includes full-speed forward- collision warning-plus; adaptive cruise with full stop; lane-departure warning with lane keep assist; rear park assist; and 9-1-1 call/assist call.

Both cars use Chrysler’s latest generation electrical architecture, called PowerNet, that was introduced on the 2011 Chrysler 300 and replaced the previous Mercedes-based system. The network has been optimized to improve data throughput allowing Chrysler Group designers and engineers to add new features and plan for future systems expansion (the architecture can support up to 40 electronic control units), according to engineers.

PowerNet—new on Challenger for 2015—retains the single 500-kb/s high-speed CAN (controller area network) but replaces the 83.3-kb/s low-speed CAN with a pair of 125-kb/s medium-speed CAN data buses, one for interior functions and a second just for telematics. The most visible component of the new telematics bus is the 8.4-in center-stack touch-screen command center. The screen works with the latest version of Chrysler’s hands-free Uconnect Access for smartphones.

The Uconnect uses PowerNet’s low-speed bus to handle personalization, instrument panel controls, entertainment and information applications such as keyless locking, smart remote start, Sirius Travel Link and iPod Control, as well as comfort and convenience controls.