Swadian, you may know busses but you know absolutely nothing about seats. There are about 10 different ways to make a comfortable seat, and not all of them use gratuitous amounts of padding. In my experience, almost all good seats hail from Europe. American seats tend to trend too much towards cush and too little towards comfort, although I would say that the best mass-produced office chair is American (that being Steelcase). My experience is that the best car seats come from France, in fact. I am particularly fond of the seats used in the final run out of French production non-sport Peugeot 505s, the Citroen XM, and the Renault Safrane. After French, I'd tend to say Swedish, particularly the Volvo 240 and Volvo S70 non sport. Of the German brands, Mercedes has the best, until they switched to non-steel-sprung seats in the very late 90s/early 2000s- but unlike the Swedish and French seats, those wear out with age- they cease being comfortable after about 500,000 miles of average use. The only Japanese cars I've ever seen with comfortable seating were the first generation Lexus LS400 (a nearly total copy of the Mercedes steel sprung unit in the W124) and oddly the seats used in mid 1980s Nissan Stanzas (no, I don't know why!).
Now, whats interesting about this? All three seats use totally different construction methods.
French seats, or at least those three, use a form of open cell foam for the seat pad, supported by an impressively heavy amount of closed cell foam, encased by a heavy gauge (bizarrely so, actually) steel pad bottom- no spring, and the metal pad support is fixed in place. I'm sitting on a velour example of such a seat right now, pulled out of a wrecked 1987 Peugeot 505 SW7 diesel in Morrisville, PA. Its very comfortable, although I have never had seats harder to pull than that of a Peugeot 505 (I had to drill out the front screws with a diamond tipped bit, and sawzall the rear tracks- try sawzalling high grade heavy gauge French steel sometime), and constructing an interface for one with that construction is very hard- but its worth it because it is so comfortable. It uses a level style lumbar support adjustment, and a hole and tooth style lever recliner (I'd guess bus seats use the same)
Volvo's 240 seat was the final one of its kind. It uses fairly thin open cell foam as a pad, and holds it into place using a lateral metal lattice and spring framework. Its very comfortable, and probably the most comfortable seat one can easily obtain (you need a ratchet set, and a Volvo 240, which are still plentiful in junkyards). It uses a tension gear wheel rake adjustment, which is slow but precise with infinite adjustments. The lumbar adjustment works on a twist wheel with screw jack-type adjustment mechanism. Because of the hard headrest, it is advisable to find a headrest cover for it, of course- you almost can't find them, but they are interchangeable with Volvo 740/760 style headrests covers, which are easily obtained. You can find them covered in just about any material- wool broadcloth, poly velour, Swedish leather, vinyl, Connolly or my favorite, the Italian Poltrona Frua leather used on the 242c Bertone.
Volvos S70 uses a much thicker foam pad, but the same steel lattice supporting it over the seats heavy steel frame. The Volvo S70 (and 900-series, 800-series, and later) seat has heavy metal framing that actually serve as an integral part of the cars crash structure in side impacts (it has heavy gauge steel tubes that press on the door sill on one side and the tranny tunnel on the other). Their height adjustment mechanism is about as intricate as a cheap swiss watch (which is an intricate thing, by the by), and it uses the same lumbar and rake adjustment mechanisms. One of these days I am going to get around to figuring out how to use the seat heater. The airbag has always worried me, but I cut and cap the wires and hope for the best.
Mercedes, on the other hand, uses horsehair pads (the smell associated with old Mercedes-Benz cars is basically horsehair mixed with diesel) with a light duty metal support frame and vertical coil springs for support. The rake adjustment uses the same tension gear system as the Volvo, and it has no lumbar adjustment. The Lexus version uses an imitation rough wool pad instead of horsehair, I assume because horsehair was too expensive. They both have the problem of weakening springs and decay of the horsehair over time.
So I wouldn't assume that a seat is uncomfortable because of its basic construction.
