Where did you get the picture? If you took the photo, then you own the copyright. If someone else took it, they own the copyright. Just because a photo shows up on Google Images (or any other site, for that matter) doesn't mean that it is copyright-free.
The owner of the copyright, though, may do with it as he or she pleases. Some people will post their photos and freely allow others to make whatever use they wish of them. Others will post them and allow others to use them as long as they give proper credit. Professional photographers generally want to be paid for every use of their photos.
To get back to your original question, though, go back to wherever you got the photo from. I'll use Google Images as an example. Click on the image, and you will get some information about it, including who posted it.
I'm a school librarian, and I daily deal with kids and teachers who feel that anything they find on Google is free for them to use. They are quite surprised when the find out that it isn't that way.
Mercury Mountaineer towing mpg 181(both sold)
1993 Foretravel U300 40'