I think in the coming decades we'll see some low/mid-market offerings that are comfortable for folks about 6' or so.

Comfort and fuel efficiency are not necessarily conflicting.

I suspect you haven't driven any small cars for a long time, would that be correct?

I have an Opel Corsa (supermini/subcompact) rental car right now, and it's both roomy, quiet and comfortable. The little 1.4L engine gets to motorway speed a lot faster than you'd think, plus it's quiet and smooth, really very little vibration felt at all, not even at 50kph in 5th gear.

The front seat pulls back enough that I literally cannot reach the steering wheel or pedals, and I have plenty of headroom (178cm/5'10").

Modern cars in all segments are generally comfortable and quiet, because that's what people want.

The Opel Corsa isn't sold in America so I'm unfamiliar with it but I had driven a variety of other small rental cars during the past few years before the pandemic. I even own a small car myself and it's good enough for short trips but for longer drives my large CUV is far more comfortable.

I owned a subcompact car and an suv. The suv was mostly for the long hauls, and I never drive the smaller car more than 30 minutes. We got rid of the suv because we realized it’s cheaper to just rent the few times of the year we really needed the extra space for those long hauls. Fwiw :)

>poor NVH experience

I suspect this is more related to the quality of the build rather than the size of the car