Reddit mentions of TomTom Adhesive Disk (2-pk.) - Black (9A00.202)

Windshield mounts typically need a flat, smooth surface to attach to which a dashboard typically isn't. To remedy this, you can buy mount disks that stick to your dashboard and provide a surface to mount to. I bought these ones:
http://www.amazon.com/gp/product/B001763SRI/ref=wms_ohs_product?ie=UTF8&psc=1
and they've been great.

I've got two preferred options I've used before in other cars, but not the Fiesta so far.

Something like this is a nice and easy mount. You can get one that grips onto a climate vent instead if that works better for you. They're easy and cheap and not as bulky.

Second option for larger holders that use a suction cup mount, buy one of these discs to create a flat surface to stick to that isn't hanging off the window and blocking your view. You could put that just to the left of your steering wheel, above the climate vent. I prefer this for Satnavs etc.

You guys know these are a thing right? You peel of the backing, it somewhere convenient, and then you and stick your phone mount or whatever right to it. They're pretty cool and don't look too out of place if you've not got something suckered to it.