The Lexus RX 400h’s hybrid engine is an amazing feat of engineering. There are many components to this engine which Lexus calls its Hybrid Synergy Drive.

• 3.3L 24-V DOHC (double-overhead camshaft) V-6 Engine with VVT-i (variable valve timing with Intelligence): This is main power source of the Lexus RX-400h. The DOHC means that the engine is a type of internal combustible engine that have two camshafts per bank of pistons. One of the pair operates the intake valves while the other operates the exhaust valves. This allows the valves to be larger and deliver more power. The VVT-i is a technology developed by Toyota/Lexus. This technology varies the timing of the intake valves helping to create an effortless and unnoticeable start and stop of the engine with minimum compression. This feature also helps to greatly reduce emmissions since it heats the catalytic converter faster to its light-off temperature.
• Electric Motor / Generator (MG1): One of the electric motors near the front drive train serves as the starter motor and provides the pathway for the engine’s power to reach the front wheels.
• Front Electric Motor / Generator (MG2): This motor serves a couple of functions. It can run with or without the engine and is also used as a generator to generate electricity during braking, deceleration and coasting (cruising down a road without depressing the gas pedal).
• Rear Electric Motor / Generator (MGR): This motor really provides the kick when accelerating. It’s pretty noticeable when this engine starts assisting the gasoline engine during hard accerlation. Additionally, this motor is used when starting from a stop, sharp turning and if the front wheels slip. The electric motor also serves as a generator during braking, deceleration and coasting. NOTE: All three motors operate automatically to provide seamless driving
• Hybrid Battery: There is a sealed nickel-metal hydride molecule battery that generates 288-volts. It is located under the rear seats. The rear seats sit a little higher than the Lexus RX 330 because of the hybrid battery. It stores regenerative energy from braking, coasting, deceleration as well as supplies power to the Inverter, which is used by the electric motors.
• Inverter: The Inverter serves a few purposes for the RX 400h. It is used to convert the battery’s DC current into AC current to power the electric motors. It also converts regenerated AC current into DC current to recharge the battery. The Inverter is also used to maintain the voltage on the 12-volt battery similar to an alternator. It can also boose the hybrid battery power up to 650 volts if needed.
• Hybrid Electronic Control System (HECS): This is the mini-brain for the hybrid system. It controls the proper flow operation of the MG1, MG2, MGR and Inverter.
• Regenerative Braking System: When you coast or brake, the MG2 and MGR turn into generators which regenerate the battery power (with no need to plug your car in). In the process of creating electricity, they also add drag to your RX 400h which helps to slow down the vehicle.
• Electronically-controlled Continuously Variable Transmission (ECVT): This transmission helps raise efficiency. Instead of the usual 4-5 gear transmission, this transmission has variable gears. It operates using less parts than a conventional automatic transmission. MG1 and MG2 are part of the ECVT. The ECVT helps maximize RX 400h fuel efficiency during long highway crusing.
• 12-Volt Battery: Last but not least, there is the battery. This battery is used to start the Hybrid Electronic Control System and operates the basic electrical system. This battery is kept charged by the Inverter.