If you want to make ur shelf look more showcarish (making up words now), then simple buy some fabric the same coulour as ur car (or colour scheme) and fill the gaps with that.
You could cut pieces of card or thin light wood to the shape of the recess (few mm smaller) then cover with spray addesive and then lay the fabric. Could try mock leather, suede, felt or even fur if it tickles ur fancey......
Trust me, would look better then chequer plate.