Add a custom field option as a menu bar item

Hi,

Is it possible to use a custom field on a menu bar? I have created fields for vehicle manufacturer and have several choices, is there a way to display all the vehicles that have the same chosen manufacturer? I would like to show all the VW vehicles on one page but the only way I can see how to do this is by using categories. The issue I have is that I have to enter the information twice. I have to tick a box to say the manufacturer and then enter it again in the custom fields so that it shows correctly. Is there a way to remove one of these steps?

So if I choose to use the taxonomies that I have created (manufacturer, price band, body style) I don't have to enter the details again in the custom fields section.

Would it be possible to have all the options on the right of the image (image here: http://demo.executivecontracts.co.uk/screen-shots/ ) appear in the "Other Information" section but still let me create specific pages that will display the chosen data such as all mercedes vehicles or all vehicles in the £300 - £399 price band or all coupe vehicles?

If it is possible, would someone be able to explain it to me as I have no idea what I am doing?

Thanks