High-Performance Hybrid Headlines Lexus’s Re-Engineered RX Lineup
Lexus looks to maintain supremacy in the mid-luxury SUV segment with 5th-gen RX models like the new 500h F Sport Performance AWD.
Electrification is a pillar of Lexus’s “next chapter.” The fifth-generation Lexus RX progresses this objective, offering four new powertrains including a high-performance hybrid and the company’s first-ever plug-in hybrid (PHEV) — though the latter is not available in the U.S. at launch.
Other “foundational elements” include bold design, intuitive technology and Lexus driving signature. Experienced firsthand by SAE Media on the hilly, twisty terrain north and west of Santa Barbara, the 2023 RX, which rides on the lighter, stiffer GA-K platform that also underpins the smaller Lexus NX, hits on all marks.
Overall, the new RX is just 4.9 kg (11 lb) lighter than the previous generation, but the GA-K platform is 90 kg (198 lb) lighter than its predecessor. Its center of gravity is 0.6 inches (15 mm) lower. Panel thickness has been reduced on the side members and front and rear door assemblies thanks to the use of higher-strength steels such as 1180-MPa grade on side rockers, 1470-MPa for the roof and 2-GPa hot-stamp steel for B-pillars.
Additional bracing at the radiator support, center floor, rear suspension towers and back door opening improves overall rigidity. Although the 2023 RX retains its overall length at 192.5 inches (4890 mm), its 112.2-inch (2850-mm) wheelbase is 2.36 inches (59.9 mm) longer and its track is widened by 0.59 inches (15 mm) to 65 inches (1651 mm) in front, and by 1.77 inches (45 mm) to 66 inches (1676 mm) at the rear. The new RX overall is 1-inch (25-mm) wider and 0.4-inch (10-mm) lower than before, giving it a more muscular stance.
Lexus says its engineers thoroughly revised the suspension to better absorb high-frequency vibrations and shocks. Up front are MacPherson struts. An all-new five-arm multi-link rear setup is reportedly more compact, which for hybrid models aids battery-pack placement beneath the rear seat while yielding more legroom (37.36 inches/948.9 mm) for rear passengers and additional cargo volume (29.6 cu. ft./0.84 cu. m. with all seats up).
Lexus’s goal for the new RX is straightforward: remain the mid-luxury SUV market segment leader over the likes of BMW’s X5 and Acura’s MDX. Lexus plans to sell about 102,000 units in 23CY, according to Mackenzie Richter, product marketing senior planner. It expects hybrid models to account for just over a quarter of the new RX’s initial-year sales, forecasting a take rate of 73% for RX 350, 17% for RX 350h and 10% for RX 500h.
First-ever RX 500h
While the RX 350h hybrid model was designed with efficiency in mind, developers envisioned drivers having a more visceral connection with the all-new RX 500h F Sport Performance AWD. A 271-hp (202-kW) 2.4-L turbocharged inline-four is matched to a six-speed automatic gearbox and integrated power control unit and electric motor. An 80-kW rear eAxle consisting of an inverter and motor provides power to the rear wheels.
Lexus opted for nickel-metal hydride batteries in both the 500h (288 V, 240 battery cells) and 350h (259 V, 216 cells), claiming their overall performance is comparable to that of lithium-ion batteries. Engineers will continue to evolve both battery types and use them accordingly, a spokesperson said.
In total, the system produces 366 hp (273 kW) and 406 lb-ft (550 Nm) – figures worthy of the vehicle’s F Sport Performance nomenclature. Lexus’s more-traditional hybrid, the RX 350h, couples the fourth-generation hybrid system with a 2.5-L four-cylinder Atkinson-cycle gasoline engine and CVT, resulting in a total system output of 246 hp (183 kW) and max. 233 lb-ft (316 Nm).
The RX 500h features a new Direct4 AWD system that utilizes the rear eAxle to provide nearly double the max output of the MGR (motor at rear axle) in the eFour AWD system employed on the RX 350h and the RX 450h+ plug-in hybrid model. Relying on sensors for wheel speed, acceleration and steering angle, the “performance-oriented” Direct4 adjusts the driving force to the front and rear wheels between 70:30 and 20:80.
Engineers explained that during departure and straight-line acceleration, the system controls the front-to-rear ratio between 60:40 to 40:60 “to suppress vehicle pitching and provide a direct acceleration sensation.” When cornering, the system distributes torque closer to the front (70:30 to 50:50) at the start of steering and closer to the rear (50:50 to 20:80) when exiting a corner. The result of this seamless transitioning: minimal body movement and extremely smooth turns that reminds this is still primarily a luxury vehicle but with a healthy dose of dynamism.
Aiding maneuverability is an exclusive-to-RX 500h Dynamic Rear Steering (DRS) system that enables the rear wheels to turn up to 4 degrees, in phase or counter phase to the front wheels depending on speed. Artificial engine sound is pumped into the cabin of the 500h to up the aura of sportiness.
F Sport models offer an Adaptive Variable Suspension (AVS) system that uses linear solenoid-type actuators to modify shock absorbers’ damping force based on driving operation and road conditions. The F Sport Handling (RX 350 AWD) and F Sport Performance (RX 500h) also sport 15.74-inch front rotors and opposed six-piston aluminum front calipers that are 2.4 pounds (1.1 kg) lighter than those used on the Lexus LS sedan and LC coupe. Other RX models get two-piston front calipers gripping 13.39-inch rotors.
While the RX 450h+ PHEV won’t be available in the U.S. until later (production-year timing was not announced), other markets will launch with the PHEV, a spokesperson said. RX’s first plug-in powertrain combines the 2.5-L four-cylinder engine with an 18.1-kWh lithium-ion battery and rear eFour AWD motor. A Euro-spec model was available for limited-distance drives at the California media event, demonstrating its ability to operate on all-electric power for short distances.
In the RX 350 (FWD/AWD), the 2.4-L inline four turbo realizes higher torque and output — 317 lb-ft (430 Nm) and 275 hp (205 kW) — thanks to technologies such as a center injection system for more stable combustion, spherical lipless pistons for high-speed combustion, and a continuously variable capacity oil pump. The eight-speed Direct Shift-8AT offers improved shift control, and the on-demand eFour AWD varies front-to-rear driving force from 75:25 to 50:50.
Fuel consumption is an estimated 27 mpg combined for the 500h AWD, significantly less than the 350h AWD’s 36 mpg but still better than the non-hybrid 350 FWD’s 25 mpg. But efficiency’s loss is performance’s gain – the 500h accelerates to 60 mph (97 km/h) in 5.9 seconds instead of 7.4 and 7.6 seconds, respectively, for the 350h and 350 FWD.
Safety and convenience
As expected for a luxury SUV starting at $48,550 for the RX 350 FWD – $62,750 for the 500h F Sport Performance AWD – there are driver-assist and safety technologies aplenty. Lexus was quick to differentiate between the RX’s “convenience” versus safety features, for legal purposes. For example, Traffic Jam Assist is categorized as a convenience feature since it’s optional and not part of the Lexus Safety System+ 3.0 that is standard on all RX vehicles.
Traffic Jam Assist provides hands-free steering assistance and can bring the vehicle to a complete stop, then resume movement as traffic allows. It automatically engages when Dynamic Radar Cruise Control (DRCC) and Lane Tracing Assist (LTA) are operating, certain road conditions are met, and the vehicle speed is below 25 mph (40 km/h).
Other convenience features include standard Digital Latch and Safe Exit Assist, which can detect an approaching vehicle or bicycle and prevent the occupant from opening the door if it senses danger, and a new-to-RX Advanced Park system, which can help with maneuvering when perpendicular and parallel parking/exiting. Four Parallel View Monitor (PVM) cameras and 12 ultrasonic sensors support the automatic control of steering, accelerator, brake and shift operations.
Lexus Safety System+ 3.0 provides additional features and an available driver monitor system. Pre-Collision System (PCS) can detect a potential frontal collision and prepare Brake Assist for increased brake force, in some cases automatically braking the vehicle to a stop. Enhanced radar and camera capabilities make it possible to detect a motorcycle or bicyclist in daytime and pedestrians in daytime and low-light conditions. PCS has left-turn intersection detection capability for a pedestrian and vehicle.
Using the vehicle’s camera and radar, Proactive Driving Assist (PDA) provides gentle braking into curves or gentle braking and steering to help control distance between a preceding vehicle, pedestrian or bicyclist. Road Sign Assist uses the camera to show select road-sign information in the IP or head-up display. Lane Departure Alert with Steering Assist (LDA) does just that, alerts and assists during an unintended lane departure.
DRCC with Curve Speed Management works in conjunction with LTA to help drivers stay centered in their lanes. Lane-recognition performance reportedly has been enhanced to realize smoother and less-disruptive steering support. Curve-speed reduction is unable to be turned off, Lexus said, but sensitivity can be adjusted via the touchscreen.
The 2023 RX is built at Toyota Motor Manufacturing Canada and Toyota Motor Kyushu. It went on sale in late 2022.