Amazon is currently selling a pair of TechMatte's very popular MagGrip Magnetic car mounts right now, for just $8.49. That's a great price for this car mount, considering it is usually around $12 or so (the original price on Amazon lists $49.99, which is not accurate).
This car mount from TechMatte is a great one because it attaches to the air vent in your vehicle and allows you to go ahead and attach your phone using a magnet. It's great because it is small and work with any smartphone out there. All you need to do is place the magnet on your phone (or inside the case, if you'd rather not attach it directly to the phone). This would also work for tablets as well, which would likely be better for Android Auto in the car. Since it's an air-vent mount, it'll be placed out of sight of the road, but where you can still reach it without being too distracted. Making it great for using for navigation, and playing music in the car - which is something we all do from time to time. Picking up a pair of them is great, as you can place one in your car and put the other in your significant other's car, or maybe your parents car, if they have smartphones.
This item is also eligible for Amazon Prime's free shipping. Which includes free two-day shipping, and pretty cheap (usually $3.99) next-day shipping if you need it extra fast. If you are not an Amazon Prime member yet, you can sign up for a free trial of Amazon Prime. You'll get 30 days free (if you're a student, you get 6 months), and then it's $99/year (or $49/year for students). Prime members do get a whole lot more than just free shipping though, so be sure to check out the full benefits.