Hold the suction cup to the windshield then say the incantation, "Abracadabra" which will remove the Repellent spell

I got my gps suction cup to stay on my windshield. and my gps is a Cobra Navone 3000 which is probably 2.5 times bigger than a garmin.

I wouldn't stick anything to the dash with glue or tape or anything adhesive, but the sun will do much harm to it. Then it'll be a mess.