No, just duplication. Most filesystems have some degree of metadata duplication anyway, for redundancy and performance.

All electric power trains have multiple "power sources". You can't run your motor straight off your generator (well you can, but we don't, because that loses much of the purpose of the electric drive train). You must have some form of stable energy buffer for your drive to pull off of. When the only difference then is the size of that buffer, you can no longer objectively define a difference.

Series hybrids are... not hybrids. Any motor drive is going to have to have a considerable energy buffer. The only real difference between the "series hybrid" and the old diesel-electric systems we've had for decades on trains, ships, and submarines is the size of that buffer. The only reason for the term to exist is because "hybrid" became a buzzword, and so existing systems wanted to join in the publicity.

A hybrid requires multiple types of engine directly providing motive force. If you have a purely electric drive train, then you have an electric vehicle, regardless of whether that electric motor gets its electrical energy from a generator.

The vast majority of the cost of the Tesla is in the battery. Drop the battery for a small energy buffer and a ~50hp generator and you're down in conventional car territory.

Some cars have brake air, and although I suppose you could consider that a fluid, the air isn't there to actuate the brakes, merely to release them. The brakes work completely mechanically on their own.

All hybrids have transmissions. No one uses direct-drive electric motors.

You only need good low end torque if you're towing something, and you're not going to be towing shit in a Prius. Cars need good mid-range torque for being able to safely accelerate to highway speeds before the end of an on ramp, and torque at speed means power, power a Prius simply doesn't have.

The typical passenger car doesn't need more than ~40hp sustained, but it needs several times that peak.

If you have an electric power train, then you don't have a hybrid. You have an electric car, and optionally a generator. Somewhere along the line a decade or so ago, someone got the stupid idea that hybrids were the future, and we've been stuck with them ever since, rather than getting a proper mass market electric.

Then you store three copies of the checksum, and compare.

Isn't that RAID6?

Sufficiently advanced RAID implementations will carry checksums of those blocks for exactly that purpose.

Again, it depends on whether it is compressed or not. A corrupted bit in video with only interframe compression will look just like a damaged JPEG. You may have an unreadable frame, or may have a corrupted macroblock or two in that frame. A corrupted bit in video with intraframe compression will smear that corrupted frame or macroblock for potentially several seconds until you hit the next I-frame to flush the image.

The common solution to this issue is software, not hardware. You have your filesystem compute and store checksums at the block level, and you give your filesystem access to redundancy, either through redundant copies on disk, or multiple parity disks. When your filesystem reads the data, it checks it against the checksum, and if needed, recomputes the data from the redundant storage. That said, you do still need ECC memory on the CPU doing those calculations for it to be reliable.

Actually, no, they won't. The chances of bitrot occurring in the same location on both your primary store and your backup, such that neither had viable data to recover, is astronomically low.

It's a small magnetic field, only providing localized protection. It is not extending thousands of miles above the planet to protect the upper atmosphere.