Acceptably Sharp

Ok, Tink mentioned I do depth of field differently than she does... and she is correct.  Mainly because I never thought to ask her before now how she did it.  Let's take this picture to start with and say I want to emphasize car number 7 (the white one).

I would use the Freehand Selection tool:

And draw around the white car like this:

Next I would go to Adjust->Depth of Field:

It would bring up the following screen.  I would adjust the blur or feather edge according to what I want done.  Usually the blur at 5 is good and the feather edge at 2.  Here I wanted to make the other stuff really blurry, so I moved it up to 10.

Pressed ok, then did a Cntrl ->D to get rid of the selection and ended up with something like here:

Mine is not as exact as hers but is something fairly easy to use if you need it.  Which way do you blur your pictures?