Second generation (2004-present)
In January 2003, Lexus unveiled the second-generation model of its best-selling luxury SUV at the North American International Auto Show, featuring a newer, sleeker body style [6]. In February 2003, the second generation Harrier (codename ACU30 and MCU30 for the front wheel drive models, and ACU35 and MCU35 for the four wheel drive models) was launched in Japan. Remaining as Lexus's entry-level SUV, the second-generation Lexus model gained as competitors the BMW X3, Land Rover Freelander and the new Infiniti FX35, following the introduction of the Lexus GX, a large midsize SUV slotted between the Lexus RX and the Lexus LX. Mechanical specification was largely similar to the first-generation Harrier, with the same engine and drivetrain combinations available (2.4 L and 3.0 L V6 with or without four wheel drive). The main difference was a new 5-speed automatic transmission with +/- shift replacing the 4-speed item in the 3.0 L V6, and the availability of "AIRS" air-suspension on the 3.0 L V6 models.

The second generation RX, now called the RX 330 for the North American and Middle Eastern markets, began sales in March 2003 [7]. The North American-market cars were initially built in Japan, with production of the RX 330 started at Toyota's Cambridge, Ontario, Canada plant in September 2003 (some North American RX 330/RX 350 models are still made in Japan). The RX 330 is powered by a 3.3 L 3MZ-FE V6, producing 223 hp SAE and (238 ft·lbf), and is available in either front or four wheel drive. "AIRS" air-suspension is again an option on the four wheel drive models. The new model sports a drag coefficent of 0.35.

The second-generation RX interior features Golden Bird's Eye Maple or Walnut wood trim, a sliding multi-level center storage console, dual-zone climate control, tilt steering column, and eight airbags. Available options include an 210-watt, 11-speaker Mark Levinson premium sound system, GPS navigation, rear seat DVD entertainment system with wireless headphones, and a panoramic, multi-panel moonroof. A power rear door is standard.

The second generation Lexus RX was launched for European and Asian markets in early 2003, where it continues to be a RX 300 and is made in Japan. Mechanical specification is more or less identical to the 3.0 L V6 Harrier, with only the four wheel drive version available. Once again, air-suspension and Mark Levinson audio can be specified. In 2005, Lexus introduced the RX 330 Thundercloud Edition for the U.S. market, featuring a horizontal-slatted grille, aluminum alloy wheels, and select luxury options as standard.

The Harrier Hybrid went on sale in Japan on March 2005, and the hybrid Lexus RX 400h went on sale in North America in April 2005 [8]. Europe and Asia also received the Hybrid RX in 2006. The RX 400h features Lexus Hybrid Drive, which combines a V6 engine and electric motors. This results in performance akin to V8s with improved fuel economy and lower emissions. The RX 400h features styling differences with the conventional gas-powered RX, including metal interior trim in place of wood, round foglights, and a different grille. For 2007, additional hybrid badging was added to further distinguish the hybrid models.

For 2007, the RX received a mid-cycle refresh consisting of a new 2GR-FE 3.5-liter V6 instead of the older 3MZ-FE 3.3-liter V6 engine, changing the vehicle's name from RX 330 to RX 350. The RX 350 also featured an updated, Generation V DVD navigation system with improved graphics, voice controlled destination inputs, and a new feature called "bread crumbs." Bread crumbs will enable drivers to retrace their steps.