I’m tired of the thousands of look-alike SUV’s out there. I don’t even want a hatchback. What I really want is a four-door sedan whose second-row seatbacks fold to make a flat floor extending into a trunk. A few times a year, I need the additional cargo space.
Does any maker have such a car? Alternatively, I am likely to get something like a Prius, with a strongly slanted hatchback. Other choices?
Older Corolla sedans (90’s) had a fold-down back seat option IIRC. Maybe they still do.
Audi A6 sedan and wagon have that. I think BMW 5 series as well.
Kia Optima, Hyundai Elantra. A lot of carmakers with 4 door sedans offer that. Our Audi A4 does not, however, but the bigger A6 does.
Are you looking for a station wagon?
Corolla still has a folding rear seat, not flat but might work, or most other mainstrean sedans
My wife’s hyundai elantra is a 4 door sedan with the folding rear seatbacks. The Sonata has the same arrangement.
Corolla with a fold down rear seat - exciting!
In that market I’d get a Corolla Cross hybrid, much more versatile.
The car w/the best folding rear seat arrangement I ever drove (rental car) was the Chevy HHR. Created a huge nearly perfectly flat space. Probably too much of an SUV for what the OP is looking for though. And they are only available as used cars these days.
TRD camry has a back seat that doesn/t fold. other trims come wiith a split folding rear seat, most of the sedan’s where the seat back didn’t fold is because the hybrid batteries or some other feature was in the way.
A lot of sedans have fold down rear seats and a pass through hatch, but are not fully open to the trunk. You might be better off looking at a hatchback if you want full width utility. Hatchbacks have a rear shelf that separates the trunk from the cabin when you don’t want the cargo area.
Or….
A minivan!!! 
A minivan is what it sounds like you need…
It sounds to me like you would enjoy something like a used Toyota Matrix or Ford Escort Wagon. Or better yet, a used Dodge Caravan. In fact, I cannot think of a more useful, versatile, and comfortable vehicle. If you can manage to find a Caravan with the 2.4L 4-cylinder engine, those can run for hundreds of thousands of miles, and are cheap and easy to work on.
My kid has suv and mentioned they might like a minivan. For hauling stuff. She’s an athletic trainer for a school.
I was one of those “wouldn’t be caught dead in a minivan” people…once. I had to fly to a wedding and rent a car that could haul at least 6 people (including the two little ones in car seats). So we ended up in a '99 or so Caravan. (Our “family” vehicle at home was an Explorer).
After easily belting the kids into the built in car seats and easily loading all of our crap into the back, and then cruising out of the airport, I looked over at my wife and said “why don’t we own one of these?” We spent the next 20 years in used minivans until the kids were gone. Can’t beat them for many things. And, especially things like the Caravans, are generally available for cheap on on the used market.
My daughter has a Prius and I can vouch for those too.
I’m old enough to remember when station wagons were the thing for families. My folks were ahead of their time and bought a new 1974 VW “microbus” (van). Even more space than a SW. Then when Chrysler brought out their “minivan”, station wagons were doomed. Every manufacturer copied them. But almost just as quickly SUV’s started being the family vehicle and you were old fashioned if you drove a MV!
Totally agree with this. The minivan is the perfect vehicle for families.
It’s just really a shame that so many people pay a lot more money in cost and fuel to avoid a “stigma”, when in fact nobody really cares.
As the OP, I will say that the minivan discussion has gone a little off-topic. I currently drive a Miata and a Mazda 3 hatchback. When I drove a Rav4, it felt like a boat. My cars are old, so “stigma” is not a factor. I try to buy the car I really like, and then keep it for 200K miles. Thus, I asked the folding seat question to see some options that I haven’t considered. A vast volume minivan also seems boat-like.
You’re overlooking that some people (like me) enjoy sporty driving. A minivan is certainly not going to provide that experience.
Sounds like they want you to buy a large vehicle and start a new family.
I never owned a minivan because of the mediocre fuel economy. An old 4-cylinder Caravan is rated at 18 mpg, my old sedans (with folding rear seats) get 22 and 28 mpg.
Too much glass in a minivan is another disadvantage; too difficult to cool in the summer.
Consider a Mazda3 Sedan, along with the Corolla and Civic. We had a Mazda Protoge for 19yrs and folding the rear seat helped with longer cargo but you were limited to the height of the opening under the parcel shelf. Buy the vehicle that you really like.