I assume you're looking at dash cams as a way to stave off excessive insurance premiums? Is fidelity really that much of a concern then, it's going to be more about being able to determine who is at fault in an accident than anything else.
I have a lady friend who's a particularly bad driver (I nearly died the first time I let her drive me anywhere), so she's using dash cams now. I'll ask her and get back to you.
My friend never got back to me - for all I know she's been in another accident and is in a coma =|
Where will you be stationed? Is condensation on the lens really a concern? I think you'd be more likely to have to deal fog on your glass than on the lens of a camera.
If you're dropping $20k on a brand new car, then I don't imagine you're limiting yourself to some $50 dash cam? The first two on this Froogle/Google Shopping search look good. IR LEDs will be valuable for night driving. This is about as much as I can help you with. :(
Somebody I knew had something like this, and it was supposedly alright.
@Rombough: there are so many car dash cameras on ebay or amazon, it is really important to have one installed so that you can avoid insurance fraud, I am using one of S.WILL brand for about 5 months, so far so good, according to your requirement, now nearly all dashcams are of HD resolution, 720p or 1080p, the compression program is very important, most of them built-in with rechargeable batteries. SD card support 4G to 32G, usually loop recording supported, it is suggest to get one with price around USD100..
The different car camera has different battery, some is built-in, some is not, the voltage is not same, most is 3.7V-5V, all use lithium battery。
Most camera has cycling recording function, this means, you just need one memory card, when the data is full, the new data will cover the old, you could set the time, such as 5 miniutes, you could also disable this function, do not let it cover data, when it's full, change the card.
Some camera support 8 GB, some support 32GB, you need select the card according the camera.
The video quality depends on the chip, there are several camera chip manufactories, the main price also depend on this.
To find the the cheap price, visit this shop, most dash camera you see on other website, you could find here.
I am in car camera market for 2 years, whatever you want to know, just ask me