http://www.edmunds.com/insideline/do/GeneralFuture/articleId=126178?tid=edmunds.il.futurelanding.latestnews..3.* You have to look closely to see the changes in the 2010 Ford Mustang, the car that will be battling the 2010 Chevrolet Camaro for our attention. Our spy shooters were able to capture video of several prototypes on the streets of Michigan, and the cars all wore several layers of heavy camouflage. There are some visible changes to the 2010 Mustang's grille, as some of these prototypes show some extra brightwork around the headlights. The hood has a slightly different shape as well, but it's probably nothing more than a little Styrofoam to hide the true design. It doesn't appear as though heavy sheet metal changes are in the works for the rest of the car, since the overall greenhouse appears unchanged. Both the coupe and convertible test mules were wearing a new set of double-spoke wheels along with relatively low-profile tires. Changes to the rear end are harder to discern. Multiple pieces of disguise hide the true shape of the rear bumper, while the lights appear unchanged from the current model. Most of the changes are expected to come under the hood. A 5.0-liter V8 will replace the current 4.6-liter V8, which should result in a decent bump in horsepower. It's not an all-new engine, though, merely an enlarged version of the 24-valve SOHC V8. The real news will be the introduction of Ford's new EcoBoost 3.5-liter V6. Its twin-turbo setup should deliver more than 300 hp while delivering superior mileage compared to the 5.0-liter V8. How Ford will pitch the new high-tech engine is tough to call, but expect some sort of special edition to highlight the new power plant. As finished as these prototypes look, the 2010 Ford Mustang isn't expected to go on sale until the fall of 2009. The EcoBoost-powered version will come even later. It sounds like a long way off, but the timing should give the new Mustang a little bit of breathing room after the introduction of the 2010 Chevrolet Camaro earlier in the year.