The 2008 Lexus RX is offered in two primary models: the RX350, which is powered by a 270-horsepower, 3.5L V6, and the RX400h, which has an advanced hybrid system combining a 3.3L V6 and an electric motor system, making a total of 268 horsepower together. The 400h's Lexus Hybrid Drive is a "full hybrid" system, meaning it can operate on electric power in some low-speed stop-and-go conditions, greatly increasing fuel efficiency. The system recovers some energy to battery packs--which are located under the back seat--during braking and coasting, and the electric motors assist the gasoline engine with extra power for accelerating and passing. Both RX models are offered in either front-wheel drive or all-wheel drive versions. In the RX350, the available full-time all-wheel drive system has a viscous limited-slip center differential and distributes power to the front and rear wheels with a 50/50-split in normal driving, sending more to the wheels with more traction when needed. In the 400h, an electric motor drives the rear wheels independently. According to Lexus, both the front-wheel-drive version of the RX350 and the RX400h can accelerate to 60 mph in 7.3 seconds. The 400h, however has superior fuel economy ratings of 27 mpg city, 24 highway. Extra attention has been paid to noise and vibration in the RX. Vibration-canceling engine mounts, an acoustic windshield, and extra sound insulation are used. There's also an available air suspension system, which has four ride-height settings, including a "high" mode for rough surfaces at under 30 mph. "Low" mode lowers ride height by 0.6 inches for improved handling, and there's also a lower "access" mode for easier entry, exit, and loading. All RX models have five-passenger seating, with a 40/20/40 split folding rear seatback that both slides and reclines. With the seats folded down, the 28.3-cubic-foot cargo capacity can be expanded to nearly 85 cubic feet. All RX models have safety systems aplenty, including vehicle stability control (VSC), anti-lock brakes with brake assist, side curtain air bags, front-seat-mounted side air bags, and a driver's knee air bag. On 400h models, there's also the Vehicle Dynamics Integrated Management (VDIM) system, which seamlessly integrates many of the vehicles systems, including the ABS, VSC, traction control, and steering assist, to enable it to more quickly anticipate the loss of control and make corrections. Both the RX350 and RX400h are available in a single very well-equipped model, which includes a power liftgate, dual-zone automatic climate control, ten-way-adjustable power front seats, real wood interior trim, and heated auto-dimming exterior mirrors. The RX offers several other innovative high-tech features that aren't common on vehicles in its price range. An adaptive front-lighting system swivels the headlights up to 15 degrees in corners, and the dynamic laser cruise control will maintain a set distance from vehicles traveling ahead. Other major options include a DVD-based navigation system with five million points of interest and an integrated Bluetooth calling interface, an illuminated entry system, a large moonroof, and an 11-speaker Mark Levinson Premium Audio System.