I am using a GoPro Hero4 Session in a Hot Wheels Experimentals Zoom-In car for the POV shots and the GoPro Hero7 Black for the other shots. The Hero7 lets me go up to 240 frame per second which looks great when slowed down.
We stuck the cameras at the bottom of a bucket of water to catch the splashes as the Hot Wheels car hits the water. I know they are meant to be able to be submerged in water but I still felt very uncomfortable actually doing it - but they didn't break so happy days!
Total Tiny Racers found a fallen tree with some perfect lines to build a high speed treetop Hot Wheels track on. Our progress was cut short by a terrible storm but we still managed to get some great runs before the rain got too bad!