It's true that 74% is not 70%, and thus strictly speaking they are within their self-imposed rules. But it's like being pulled over by a cop for going 4 miles over the speed limit. Strictly speaking, you broke the law. But is pulling someone over at 4 miles over the right thing to do? Yes, 74%...
OK, as far as I’m concerned, it’s official now: BMW has the worst warranty ever! My i3’s battery is down to about 74% of what it was when new, 5 years and about 30K miles ago. The dealer told me BMW refused to change the battery under warranty because it had to be under 70%. I filed a complaint...
You can also use a GoPro, which can be mounted anywhere and controlled from the GoPro app running on an iPhone but accessed via the iDrive system. Video is recorded but preview is disabled when the vehicle is in motion, though.