The rear seats should recline in addition to folding down/forward. This is essential when driving duty is being shared, so those not driving can get some shut-eye. It is currently very uncomfortable to attempt to sleep in the rear seats.
This is a feature of most family cruisers we have encountered, e.g. Lexus RX series, Honda C-RV, Honda Odyssey, various other minivans. It does not seem expensive to implement greater freedom of motion with selectable stops.
Notes from Moderator:
If the rear seats are folded down, you can have an extended area that is flat that goes into the trunk. A number of owners have slept in this area that is far more comfortable than any partial recliner if using a cushion.
Minivans and SUVs typically have room to offer a partial rear seat reclining feature, while only a couple of large stretch sedans offer partial reclining (Lexus LS600 comes to mind).
Tesla offered an Executive rear seat option in 2015 on the Model S. The sales were so low that it was discontinued. These did not recline. The Model X second row has seats that recline.
I am a model S owner. I've slept in the trunk more then once when doing a road trip. It's not as easy as it sounds. With back seats down, there is still a significant height difference and it's really hard to get in and out of.
For a long trip, the trunk area is likely to be full of luggage, etc. and hence not available for fully reclined sleep. We have slept overnight in the back with seats folded, and it takes some customization to level it sufficiently, as there is about a 6 cm step between the rear deck and the folded seats. Of course, you have to move stuff out of the trunk first, or keep it in the frunk.
Moderator is incorrect that this feature is rarely found in sedans. As I mentioned, the Lexus RX series, the Honda C-RV, and other crossovers have this feature. We know it is useful because we have used it. I am certainly not proposing a stretch limousine approach to this.
Of course the front passenger seat may be available, but it may be difficult to escape paying attention to navigation when sitting there. And the driver may prefer to have navigation assistance rather than a sleeping alternate driver in that seat. I'm talking about a high occupancy situation here, not just a traveling couple.
In my opinion, the moderator here has a tendency to be more opinionated than is appropriate to this kind of site. Also, the estimate of cost to implement seems to be inflated in inverse proportion to the moderator's opinion of the feature.
To me the benefit would be kids in the back being able to recline and sleep. Current setup makes the back seats very uncomfortable for road trips with the wife in front and two kids in back, even with superchargers all over the place here in California. So we take the ICE SUV instead.