There is a small window behind the rear door that helps a little, but yeah there's a little bit of a blind spot. However, unique to the Solterra (not available on the bZ4X) is the digital rear-view mirror that eliminates all blind spots to the rear. Not surprised that Subaru insisted on that, if only on the touring trim.
I'd say (without having been in the actual car) there's a larger blind spot in the Solterra than any other vehicle I've ever owned, and the little windows in the back are mostly to make the back seats seem more spacious.
I'd also argue the side view mirrors (if adjusted properly) are your main source, in any car, to eliminate blind spots, but you really should be able to turn your head to double-check what's beside you. Unfortunately, you really can't see out of those tiny windows from the driver's seat to help reduce the blind spots.
<rant>
I also have a bit of a pet-peeve about blind spot warning lights because most people don't adjust their side view mirrors to properly reflect what's
beside the car (their blind spots) and instead just look back behind the car (that's what the rear view mirror is for). So they rely on the light more than actually seeing the vehicle. I always look for eyeballs in side view mirrors of cars I am driving past, but sadly in most cars I see the top of the steering wheel instead of someone seeing me in their blind spot.
</rant>
So despite the digital mirror having no obstructions (headrests) and a much larger field of view than the optical mirror (I wish I knew some actual numbers), a rear view mirror is only to see behind you and can't see beside you in your blind spots.
Sadly, the digital rear view mirror is one of the main reasons I reserved the Touring instead of the Limited, mostly because of the lack of a rear wiper more than the other visibility issues.
Tunnel vision using optical rear view mirror
