Photoshop
I have a professional version of Photoshop so I hope mine is the same as yours:
Select the body of the car by drawing a path, or using the lasso tool. Select the color you want in the picker palette and make sure it's the foreground swatch in your tool bar. Now go under the edit menu and select fill. Make sure it says "color" in the pull-down menu where it normally says "normal." Click ok. Now you should have colored the body of the car and kept all the highlights, midtones and shadows.
minimott
I have a professional version of Photoshop so I hope mine is the same as yours:
Select the body of the car by drawing a path, or using the lasso tool. Select the color you want in the picker palette and make sure it's the foreground swatch in your tool bar. Now go under the edit menu and select fill. Make sure it says "color" in the pull-down menu where it normally says "normal." Click ok. Now you should have colored the body of the car and kept all the highlights, midtones and shadows.
minimott