I have searched on this a few times. Seems the best way is to buy a cigarette lighter style charger and disassemble it. I was wondering if something like this might work though: eBay DC-DC step down buck converter
I'm only interested in powering it while the car is running. I've got a few different functions being managed by an uno, and it will probably be switched to a pro mini once it's finished up.
I don't know much about dealing with a noisy supply, so if that part won't do the job, I'll buy a cigarette lighter to hack up. I just might be building a few more of these, so an off the shelf solution would be preferred.
Thanks in advance!