Best GoPro mounts for in car?
 

I have tried a suction cup mount but perhaps I got a cheap one because it came off the window quite frequently and shook even when tightened.

I'd love to get one that had a shot of the dashboard and over the hood. Headrest mount perhaps?
Any recommendations?

try ram mounts with a gopro tripod adapter

The GoPro branded suction cup is not bad. For more heavy duty stuff I use a delkin fat gecko (dual). They make a triple as well but it's overkill for a gopro/compact camera.

If you want something on the cheap why not use the adhesive + clip? they're obviously more permanent of a solution but if you have somewhere you can mount it they work pretty good.

Headrest mount, might be best to DIY. Good ones were >$50 last I checked