Depends on the mode, but yeah- recording 1080P @ 120 FPS will rinse a standard GoPro battery in an hour. I have one of those battery BacPac's which gives you another hour, but have another 2 batteries.
That said, the last video of yours I saw, you had 4 cameras.... Perhaps better to hardwire them in that case lol. You could even get one of those rechargeable battery packs for £20 and secure it to the rear seat/headrest so you don't need cables going all over the car.
I've just added a 4Black and Hero Session to my collection so will be running 7 cameras and a digital field recorder next time out LOL I can't be bothered with batteries, charging, recharging, swapping over etc. The positions I have my cameras in are pretty much fixed so I have a spider's web of USB cables running all over my car, tucked away behind trim pieces, and all ending up at a junction box/power socket bank in my glovebox.
No matter what resolution I find 2 hrs about the max you can expect from any GoPro device...and that is just enough for a trackday for me. I like to film everything, all the time the car is running so that if necessary I can attach data logs/dials and see what is going on, and that adds up to a lot more than 1hr per day!
Cheap cameras? I can't even remember, I tried a few before I got my first GoPro HD Hero2 years ago and got fed up of them dying without warning, crashing, randomly resetting...hence biting the bullet and going for the HD2.
I now have ready to strap to my car whenever needed;
HD2
Hero
Hero Session (this is the only one I will run from a battery as it will be on my helmet, front bumper, door mirror, rear bumper, roof etc.)
4Black
2x A118C dash cams (recent replacements for my G1WH which have been great for a couple of years but now, as with other cheap cameras, randomly crash and/or reset)
Sony FDR-AX33
Zoom H1
Goodwood in July cannot come soon enough!