For truck guys Matt O'Leary and Pat Schiavone, P415 was just another assignment. To their bosses in Dearborn, though, P415-the internal codename for the 2009 Ford F-150-was almost certainly Ford Motor Company's single most important new-model design and development program this decade. Last year, one in three vehicles carrying the Blue Oval badge sold in America was an F-Series. On a world scale, the F-Series accounts for 13 percent of global Ford Motor Company sales.

Chief engineer O'Leary and chief designer Schiavone seem remarkably relaxed about it all, however, as they walk us through the detail of the new F-150. That's because they're old hands at this game: They and their teams worked together on the F-150 that launched in 2004. O'Leary's spent 30 years at Ford, most of it working on truck programs. Schiavone grew up around trucks-his father was in the construction business-and has helped design three generations of F-150.

The Backbone

Both men also understand that full-size-pickup buyers are among the most conservative consumer groups in the auto biz. Which is why the 2009 F-150 is a carefully considered study in evolution, not revolution. It starts with the fully boxed frame, which is 25 pounds lighter and 10 percent stiffer, thanks to hydroformed high-strength-steel side rails. The double wishbone short- and long-arm front suspension with coil-over shocks shares components with the 2008 Expedition. The 36mm front stabilizer is hollow and eight pounds lighter than the previous component. At the rear are six-inch-longer leaf springs, the extra length forward of the axle centerline to provide better lateral compliance and reduced rear-axle steer.So far, so truck. But O'Leary's engineering team has delved into Ford's electronic goody bag to give the new F-150 a level of refinement, security, and user-friendliness unheard of in a pickup truck a few years ago. Ford's traction- and stability-control systems are now standard on all F-150 models, from the base work truck up. In addition, Ford's software geeks have figured out a way of using these systems to detect trailer sway: By tracking the yaw motions of the truck, the system can sense whether a trailer is swinging and then use a combination of braking and engine torque control to bring it back under control. If the F-150 is fitted with Ford's optional Trailer Brake Controller, the system also will use the trailer brakes to bring things back under control. Additionally, the new six-speed automatic transmission includes a towing mode that not only holds a lower gear for hauling up hills, but cleverly works to hold the rig to a constant speed on a downhill stretch.