A couple if ways.
If you have V26 then it's a menu selection to do this (and if you don't have V26, get it. The interface is much improved).
If you don't have V26 then all you need to do is go to "Information" and select something more obscure such as BMW dealerships in the area. The system remembers that last Point of Interest that you selected and will show the icons for that. In your case, the last Point of Interest you looked at would be a gas station.
If you aren't sure what I mean by V26, see
http://www.xoutpost.com/showarticle-59.html and
http://www.xoutpost.com/navigation-sy...-released.html
:xoutpost: