Use the eraser and take out the good chunks that aren't near the car. As you get closer to the car, use a smaller brush. Use a very small, soft edged eraser when your right around the car so you don't get any jagged effects. Finally, go in small steps, no sense in having a real nice, smooth section going only to get a little too close and wipe out a bit of what you wanted; undo is your friend.
If the color of the car doesn't blend in with the house at all you could try using the Extract Tool. Go into Image > Extract, checkbox "Smart Highlighting" and start going around the car. The Magnetic Magic Wand works similar to this as well.
This is really my first time posting in here and my Photoshop experience isn't very much, so I wouldn't say these are the best ways.