Lexus has officially launched the 2006 RX 400h, due to go on sale in April 2005, and has provided some additional information about its design and performance.

Based on the RX 330 SUV, the RX 400h uses an enhanced version of the Hybrid Synergy Drive system that combines the 3.3-liter V6 gasoline engine with a high-torque electric drive motor-generator plus a rear electric drive motor-generator to provide on-road all-wheel drive (AWD) capability.

The combined full hybrid system delivers 268 hp (200 kW) and 3,500 lb-ft (4,740 Nm) of axle torque at launch. The luxury hybrid accelerates from zero to 60 mph in 7.3 seconds—about 0.5 seconds quicker than the RX 330.

Toyota estimates the RX 400h combined fuel economy at 28 mpg—a 33% improvement over the RX 330. (By comparison, the Ford Escape Hybrid 4WD achieves 31 mpg combined.) Its city fuel economy of 30 mpg is 67% better than that of the RX 330, reflecting the benefit provided by the hybrid drive in stop-and-go city driving.

The RX 400h will be rated as a Super Ultra Low Emission Vehicle (SULEV) in California (Tier 2 – Bin 3 under the EPA schema).

The engine in the RX 400h is based on 3.3-liter V6 in the RX 330 but with revisions to promote smooth integration with the hybrid system. These include revised calibrations to the Variable Valve Timing with intelligence (VVT-i) and Electronic Throttle Control (ETC) systems.

The AWD hybrid system adds a third motor (MGR—Motor Generator-Rear) to the two (MG1 and MG2 used in the Prius).

• MG1 functions as a generator/starter, and controls the transmission ratio

• MG2 is a 167 hp (123 kW) motor that delivers 247 lb-ft (335 Nm) of torque to the front wheels, and performs regenerative braking.

• MGR is a 68 hp (50 kW) machine that provides up to 650 lb-ft (880 Nm)of additional drive torque on demand to the rear wheels. It also provides regenerative braking functions. The system electronically varies front and rear torque distribution depending on traction conditions.

The hybrid system uses a 288-volt Ni-MH battery pack that fits under the rear seat. The battery’s power is directed through a boost converter that raises voltage to 650V DC.