http://www.dailytech.com/article.aspx?newsid=12368

Ford looks to smaller displacement engine with turbochargers to boost fuel economy in its full-size truck

When people think of the Ford F-150 full-size pickup, most think of a hulking, crew cab, 4x4 cruising down the street with a Triton V8 under the hood. At the very least, you'd expect to see a base model version with Ford's venerable 4.2 liter V6 providing the motivating force for the vehicle. With gas prices putting many Americans near the breaking point -- and sending sales of full-size trucks and SUVs downward -- Ford is looking to downsize its powertrain offerings for the F-150. According to Ford Product Chief Derrick Kuzak, the F-150 may be offered with an EcoBoost four-cylinder engine. The turbocharged four-banger would provide in excess of 260 HP and 300 lb-ft of torque. For comparison, the current base V6 provides 202 HP and 260 lb-ft of torque, while the smallest V8 offering is rated at 248 HP and 294 lb-ft of torque.
Dan Kapp, Ford's Powertrain Research and Advanced Engineering Director, went on to praise EcoBoost turbocharging and stated, "In probably the most extreme cases, we’re going to be downsizing on the order of 40, 50 percent. That would take, for example, a three-liter V6 down to a two-liter four-cylinder engine. A 2.5-liter four-cylinder could be something on the order of 1.5-liters."
With these factors, an EcoBoost six-cylinder engine can produce like an eight-cylinder and a four-cylinder engine like a six."
The EcoBoost 4-cylinder engine for the F-150 would only be available on a select few trim levels. According to PickupTruck.com, the engine will likely only be made available on the regular cab 4x2 and 4x4 models. The introduction of the EcoBoost four-cylinder engine will also help to boost Ford's Corporate Average Fuel Economy (CAFE).
While the four-cylinder EcoBoost variant may boost economy on the low end, Ford is also preparing a 3.5 liter V6 EcoBoost engine for the F-150 in 2010. The engine eclipses the current range-topping V8 in the F-150 with 350 HP and 390 lb-ft of torque -- this compares with 300 HP and 365 lb-ft of torque for the current 5.4 liter V8 engine.
The EcoBoost V6 will also manage to better the V8 in fuel economywhen paired with a 6-speed automatic transmission. Fuel economy is said to rise from 14 MPG /19 MPG (city/highway) to at least 16 MPG / 22 MPG.