[5] Bösendorfer pioneered the extension of the typical 88-key keyboard, creating the Imperial Grand (Model 290), which has 97 keys (eight octaves).

Ferruccio Busoni initially ordered this innovation in 1909 as part of a custom piano, as he wanted to transcribe an organ piece that extended to the C below the standard keyboard.

[8] This innovation worked so well that this piano was added to regular product offerings and quickly became one of the world's most sought-after concert grands.

The extra keys, at the bass end of the keyboard, were originally hidden beneath a hinged panel mounted between the piano's conventional low A and the left-hand end-cheek to prevent their being struck accidentally during normal play; more recent models have omitted this device and simply have the upper surface of the extra natural keys finished in matte black instead of white to differentiate them from the standard 88.

[9] There are also two other features of Bösendorfers that are shared with only a few other piano brands: one is a removable capo d'astro bar in the treble, which facilitates rebuilding of the instrument and, Bösendorfer says, provides greater acoustic separation from the plate, decreasing tonal absorption; the other is single-stringing, providing each string its own individual hitch pin on the plate instead of connecting it to a neighbouring string.

The requisite equipment can be fitted to most Bösendorfer pianos to allow the direct recording of pieces while capturing all the keyboard velocity data as a .boe file.

[16] Under the ownership of Kimball, Bösendorfer built and sold a small number of Stahnke Edition automatic reproducing pianos based on 3 of the 'Imperial Line' models 225, 275 and 290.

These instruments were designed to work with either performances stored on cassette tapes as digital data, or with an attached MS-DOS IBM PC computer.

The SE system instruments were the first commercially available computer-controlled "player piano" capable of accurately reproducing both the notes and intensity of a performer's playing.

[19] Bösendorfer produces a limited number of Artisan Models annually, each available for order only during the calendar year in which it was developed.

[20][21] Three notable architects who have designed Bösendorfer piano models are Theophil Freiherr von Hansen (1866), Josef Hoffmann (1909) and Hans Hollein (1990).

There were only two Hans Hollein 225 models produced in 1990; one can be found in the lounge of the Grand Bohemian Hotel in Orlando, Florida.

[28] Minimalist composer Charlemagne Palestine chose a nine-foot Bösendorfer as the vehicle on which to perform his 1974 composition Strumming Music.

Released as his first compact disc in 1991, it features in excess of 45 minutes of Palestine forcefully playing two notes in rapid alternation, slowly expanding into clusters, with the sustain pedal depressed throughout.