The 2024 and newer Lexus RX 500h AWD was the first vehicle from the brand to showcase their all-new high-end turbocharged hybrid powertrain option that takes power and driving enjoyment up a few levels from the base hybrid powertrain in the RX 350h.
The powertrain starts with the Toyota / Lexus corporate T24A-FTS 2.4-liter turbocharged inline 4-cylinder engine that features both port and direct fuel injection – a system called D4S. The engine also has dual variable cam timing and an 11.0:1 compression ratio and by itself offers up 271 horsepower and 339 pound-feet of torque.
It comes mated to a conventional 6-speed automatic transmission instead of an ECVT like other Lexus hybrids. There is an electric motor sandwiched between the engine and transmission however and an additional electric motor drive unit at the rear axle for all-wheel drive. Therefore you will not find a mechanical driveshaft between the front and rear power units. A 288 volt Nickel-metal hydride battery pack is located under the rear seat.
The total combined system output is 366 horsepower and 406 pound-feet of torque which provides spirited performance and a traditional driving experience with the feel of real transmission shifts. Efficiency is rated by the EPA at 27 mpg city, 28 mpg highway and 27 mpg combined running on 87-octane regular unleaded fuel.
Following the airflow the intake charge starts at the front passenger side of the engine bay, drawn in through a snorkel and resonator chamber then into the air-filter box low at the front. From there it travels past a mass-airflow sensor and to the rear of the engine into the turbocharger.
Once boosted air then travels up over the engine to the front where it is cooled by an air-to-water intercooler and then into the engine through a composite plastic intake manifold. Atop the engine you can see components of both the port and direct fuel injection.
A fuel rail for the port fuel injectors is seen somewhat under some components at the front. The large shiny aluminum fuel rail on top along the spark plug coil packs is for the direct injection. Once the combustion takes place it exits through the turbocharger which features an electronically controlled waste-gate and directly into the catalyst assembly.
DIY maintenance on the Lexus RX 500h is as straightforward as most any modern vehicle with only a couple exceptions. The majority of its fluids can be found at the passenger side with engine coolant at the furthermost outboard location. Turbocharger intercooler coolant is just to its right. Ahead of both is the windshield washer fluid.
The engine oil filler cap is at the top passenger side of the engine and can be accessed without removing the sound cover. The oil dipstick is at the front of the engine noted by its bright yellow handle. The oil filter must be accessed from below.
The brake fluid reservoir can be found at the driver side near the strut tower. As with all fluids, always consult your owners manual for the type, grade and amounts you will need.
Just ahead of the brake fluid reservoir is the engine computer and to its right is the main fuse box. It opens easily with the pop of a clip and inside you will find and included fuse removal tool to help you out.
The air-filter is located down low on the driver side ahead of most of these components and can be easily replaced by popping a couple clips. No tools are required.
Of note, the electric cooling fan is mounted at the back side of the radiator and should be treated with respect as it can turn on at any time if the engine is warm and has been running even with the engine is turned off. Also be careful working with or around the orange wiring harness that connects to the hybrid electric motor and control components as it handles some 288-volts.
