Pickuptrucks.com has a report about the Ford 5.0L turbo V8 with both gasoline and ethanol injection. The project is called "Bobcat."
The engine runs primarily on regular gas, with a separate ethanol injection circuit. The purpose of the separate ethanol injection is to cool the gas/air mixture, allowing higher turbo boost and higher compression ratio. The cooler mixture also allows the engine to run lean without producing too much oxides of nitrogen.
The reason this note is posted in the diesel news section is that the power produced by the Bobcat engine may surpass that of production diesel engines, with good fuel economy, and without expensive particulate traps or urea injection system to control emissions. If the engine proves to be durable like a diesel, there would be little reason to put diesels in light and medium duty trucks.
For example, the Bobcat 5.0L turbo V8 is expected to produce 500 hp and 750 lb-ft of torque. That's significantly better than the current 6.4L PowerStroke diesel.
One problem is availability of ethanol. Under light load, the fuel in the ethanol tank will last hundreds, even thousands of miles. Under heavy load, however, the ethanol is used more quickly, and might only last 100 miles. The truck will continue to operate on gasoline only, but power will be significantly reduced until the ethanol can be replenished. ("No, officer, that bottle is not filled with moonshine, it's my emergency ethanol supply!")
At present, pure ethanol is not readily available at service stations. E85 can be found at more locations, but the fuel delivery infrastructure will have to be updated before the Bobcat engine will be a workable solution.
Read the report here
http://news.pickuptrucks.com/2009/06/sneak-peek-ford-bobcat-dual-fuel-engine.html