Toyota's Tundra is available in a number of variants to meet different truck users' needs for 2007, including three different engines with two- or four-wheel drive, three cab styles (Regular, Double Cab, and CrewMax), three bed lengths (short, standard, and long), and three wheelbases. Each of the three beds are about 22 inches deep and shaped to accept 2x8-foot lumber dividers. The steel tailgate is designed to be opened and closed with just two fingers, and there's also an available Deck Rail system for more individualized cargo arrangements. Regular cab models include a standard two-door arrangement and one row of seating, while the Double Cab offers smaller rear doors for occasional back-seat passengers; the big CrewMax brings full-length rear doors and seating comparable to that offered in full-size SUVs. CrewMax models also have a unique reclining and sliding rear seat, while Double Cabs get a folding seat bottom that allows for a flat storage area when the seat isn't in use. The base engine on regular and Double Cab models is a 236-horsepower, 4.0L V6; CrewMax models get a standard 4.7L V8 making 271 horsepower. A new 5.7L "iForce" V8 making 381 horsepower and 401 lb-ft of torque is available on all models. Each of the engines meet the more stringent ULEV II emissions certification and run on 87-octane gas. The 4.0L and 4.7L engines are paired with a five-speed automatic transmission, but the 5.7L upgrades to a six-speed auto. All Tundras have a rear suspension design that maintains a level ride height even with a full load; underneath are fully boxed frame rails in front and rolled C-channel members in back. When properly equipped, the Tundra can tow up to 10,800 pounds. The Tundra has more standard safety features than most of its competitors. Front-seat side air bags are standard on all models, along with roll-sensing side-curtain air bags. Also, four-wheel disc brakes with vehicle stability control are standard on all Tundras. While the safety features are standard across the line, the Tundra ranges from basic to very luxurious inside depending on the trim level, starting at the very frugal base model and going all the way up to the very well-appointed Limited. Regular cab models are available in base, DX, and SR5 trim levels, while Double Cab and CrewMax models are offered in SR5 and Limited levels. Inside, all models have a tilt/telescope steering wheel, door handles and control knobs designed to be operated with gloves, and a huge upper glovebox designed to hold a Thermos, plus a center console large enough for a laptop or file storage. Interior power outlets stay live for two hours after the ignition is switched off. The Limited model includes all the interior luxury features offered in full-size SUVs, such as dual-zone climate control, heated power front seats, and a 440-watt JBL surround-sound system. A TRD (Toyota Racing Development) Off-Road Package is optional on Regular and Double Cab V8 models, bringing an off-road suspension, off-road tires, engine skid plates, and fog lamps. Other notable options include a DVD-based navigation with rearview camera, rear-seat DVD entertainment system, and larger 20-inch wheels.