The Toyota Harrier is a midsize crossover SUV manufactured by the Toyota Motor Corporation. In North American markets, it is sold as the Lexus RX series (such as the RX 300, RX 330 and RX 350). It is based heavily on the Camry platform, which it shares with the Kluger/Highlander. The Harrier was introduced in Japan in 1997 and the RX 300 at the 1998 North American International Auto Show. It quickly became the Lexus's best-selling model. It was one of the first crossover SUVs on the market and served as a model for following designs.

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 February 2003 in Japan. Mechanical specification is 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 is 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. A JBL sound system is an available feature.

The second generation RX, now called the RX330 for the North American and Middle Eastern markets, was introduced at the 2003 North American International Auto Show. 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. The RX 330 is powered by a 3.3 L 3MZ-FE V6, producing 230 hp SAE (171 kW) and 328 Nm (241 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, and interestingly, a Mark Levinson sound-system is available in place of the JBL system found in the Harrier.

For European and Asian markets, the second generation RX was launched in early 2003, where it continues to be a RX300 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.

The Harrier Hybrid went on sale in Japan on March 2005, and the hybrid Lexus RX 400h went on sale during the 2006 model year in North America. Europe and Asia will also receive the Hybrid RX during 2006.

The third generation RX, or the RX 350, will use the same body as the RX 330. However, it will have a 3.5-liter V6 instead of a 3.3 liter engine. It will also feature an updated DVD navigation system with better graphics, voice controlled destination inputs, and a new device called "bread crumbs." Bread crumbs will enable drivers to retrace their steps.

The Lexus RX 400h is an automobile assembled by Toyota Motor Corp. under the Lexus brand name using Toyota's Hybrid Synergy Drive technology. It is called the Toyota Harrier Hybrid in Japan. After first being introduced in January 2004 at the North American International Auto Show, it would become the world's second mass-produced hybrid SUV, after the Ford Escape Hybrid. In November 2004, Toyota announced the American launch of hybrid Lexus/Toyota SUV will be delayed to the 2006 model year, with European and Asian launches during 2006. The Toyota version of the same car debuted in Japan on 22 March 2005, the same day as the Toyota Highlander Hybrid.

Toyota will price the RX 400h/Harrier Hybrid at a substantial premium over the non-hybrid RX300/RX330/Harrier. The list price in Japan ranges from 4.095 million Yen to 4.62 million Yen. In US, it will be priced at US$49,185, which is a $5,600 premium over a similarly-equipped RX 330.

The gasoline-powered part of the engine system is a 3.3 L 3MZ-FE V6, very similar to the one found in the RX 330. It produced, in the case of the Harrier Hybrid, 211 hp JIS (155 kW) and 288 Nm (212 ft·lbf). The petrol engine is aided by a maximum of two additional electric motors, one driving the front wheels, producing 167 hp JIS (123 kW) and 333 Nm (245 ft·lbf) and connected to the CVT gearbox, and the other driving the rear wheels, producing 68 hp JIS (50 kW) and 130 Nm (95 ft·lbf). The whole system, called Hybrid Synergy Drive, produces a maximum of 272 hp JIS (200 kW). Under normal driving conditions, only the front motor and petrol engine will be used. The rear motor will only be used under full-throttle acceleration or when the front wheels lose traction. The petrol engine will switch off automatically and the car will be electrically driven when either stationary, decelerating, or being driven at a slow speed. A Ni-MH battery is responsible for powering the motors, and it is charged during deceleration.

The assistance of the electric motor increases the vehicle's performance; the 400h/Harrier Hybrid can reach 60 mph (97 km/h) in less than 8 s, quicker than the petrol-only RX. Despite the increased performance, the RX 400h/Harrier Hybrid consumes roughly the same amount of petrol as a compact four-cylinder saloon and it qualifies as a Super Ultra Low Emission Vehicle (SULEV) in America. Under the Japanese "10.15 mode" fuel consumption standard, the Harrier Hybrid can run 17.8 km per litre of fuel (compared with the standard coil-sprung V6 3.0 L Harrier, which returned 9.4 km/L). In Japan, it qualifies as a "4-star" LEV-car, where it produces 75% fewer emissions than the standard specified in Heisei 17 (i.e. year 2005).