I have often eaten roadkill pheasant. We lived in the middle of rural Northumberland, and there was one road on my way home which often had deceased pheasants on it. I knew they hadn't been there long, because they weren't there on my morning run to work. I decided to do it the easy way and just peel back the skin and take the breasts and cut off the legs, discarding any bruised bits. Delicious, even just fried in some oil and butter. Why would you worry about disease or anything? Your eyes and nose will tell you if there's anything wrong. Pheasants have a nice life, living in the countryside, being fed grain by the gamekeeper as a supplement to what they forage. What is wrong with eating them if they are killed by a car as opposed to a gun?