Liftbacks are basically (more or less) sedan shaped cars, but that have a fully opening hatcback-styled trunk, instead of the standard tiny one on most sedans, so cars like Audi A5 Sportback, BMW 4 Gran Coupe, Skoda Octavia&Superb, VW Arteon, Ford Mondeo,etc.
Liftbacks are not the same as regular hatchbacks (Fiat Panda, VW Up/Polo/Golf, Audi A1, Toyota Aygo,…) and they are not shootingbrakes (ones that look like wagons, but with a curvy back), they all are different categories, though I saw one website that lists 10 “liftbacks” and pretty much all cars are just small hatchbacks…
Most of my favorite cars are sedans like the BMW 3 and 5 series and Audi 4 series, but for whatever reason they only have those tiny trunk openings, so if you want a BMW 3/5 which you can actually use for transporting medium and larger things from time to time, which every family and even single person needs ocassionaly, you have to skip the sedan and buy either a wagon or the weirdly shaped and too long 3&5 Gran Tourers, whose sole purpose is a fully opening trunk. There’s also the option of the BMW 4 Gran Coupe, but the drawback is a tiny headspace for back passengers.
On the other hand an economy brand like Skoda has both the Skoda Octavia (equialent to VW Jetta sold in USA) and the more luxury and larger Superb (Passat’s cheaper brother) that have a normal sedan-like shape, that have normal headspace for back passengers and that have the practicality of a hatchback trunk.
Why is it rocket science to implement this into other, at least entry-level sedans? The american VW Jetta I mentioned, even though it’s literally the same shape and even has same backlights as the liftback Octavia…is not a liftback and instead you just get the tiny trunk opening, even in a car who was already proven succesfull as a liftback.
It’s weird to think that a large premium BMW 5 or Audi A6 can carry less things than a tiny supermini VW Up! with rear seats folded down. If you have a large dog that you need to carry in a transport box to the vet or something, if you buy some small furniture,etc, then you can use a sub 10k$ car, but you can’t use a +40k $ beast that boasts with luxury and cubby spaces. If liftbacks were more popular, there probably wouldn’t even be such a craze for Crossovers, since people would get all the space they want, without having to buy a hatchback or a wagon.