Cup holder mount (depending on where exactly those are located on your car) seems less than ideal if you are using the phone for Navigation.
I use the Mountek CD slot mount same as the photo posted above (except mine is stock,
[email protected] modded his to combine it with the EVO 4G LTE dock). On my car, the position is similar to the above pic, up high on the dashboard, for good viewing if using for Navigation.
If your AC is on, and the vents are anywhere close to the phone (even if not pointed directly at the phone) I wouldn't worry much about overheating the phone, even if in direct sunlight. Pretty sure the phone will shutoff if it starts to overheat. Given, its a heck of a lot sunnier and warmer in Florida than Boston, but I haven't had any issues with direct sunlight up here. Leaving something on the dash with the windows closed, and the car off is one thing. But if you're driving the car, and the AC is on, or even the windows open, I wouldn't worry that much about the temperature.
---------- Post added at 11:40 AM ---------- Previous post was at 11:35 AM ----------
Actually, they are well made, solid and pretty nice material.
+1 to this. The Mountek mount is very well made, and works great. Most every cupholder, air vent, suction cup mount is crap in comparison. You can see from the numerous positive reviews on Amazon, many of which compared it to other mounts, and found the Mountek superior. If you don't use your CD player, its a great solution. It doesn't harm the CD player at all, aside from possibly deforming the fabric or brush "dust guard" in the slot.
http://www.amazon.com/Mountek-Universal-Smartphone-Blackberry-Motorola/dp/B004G1L52Q/ref=sr_1_2?ie=UTF8&qid=1339601834&sr=8-2