The mail merge toolbar makes using mail merge a little easier
Take particular note of the sixth button from the left. I've highlighted it for you above. Click this button to open the Insert Merge Field window. Alternatively, you can click the "More Items" option in the sidebar. Either way you do it, Word opens up a window from which you can select fields from Excel to add to your flyer. As you're typing your flyer, use this window to add a field where you would normally put in specific information about a vehicle. For example, rather than typing in the price of a vehicle, insert the "Price" field instead.