Attached is screenshot with the images highlighted. The image is 159px wide. The truck is about 145px wide. So you have 14px of white space.
I would get rid of the sideboxes that you are using which are causing some dubious code and have a look at the blank sidebox mod and use that.
But maybe I am misunderstanding what you are trying to do.
At the moment the css for the class sideboxContent looks like:
Code:
.sideBoxContent {
background-color: #ffffff;
padding: 0.4em;
}
Which means that the box that the image is sitting in has some padding. If the image is the width of the containing element it will not fit properly. The width of the containing element needs to be the width of the image plus the padding.
So, perhaps you need to get rid of the padding?