This data from Vacuumland thread 33135 shows the improvements from the Z320-series to the Z700-series: (link:
https://www.vacuumland.org/cgi-bin/TD/TD-VIEWTHREAD.cgi?33135_26)
1972 - Z320 Jumbo-matic: first vac w/the same record performance of 2000mm WS and 2.5 cubic meters per minute using only 800W, programmed vacuum performance, automated pop-open cover
1975 - Z325 Jumbo-matic: first vac w/rotating furniture-cleaning accessories, automatic breakdown function in case of missing dust bag, changeable automatic nozzles 1980 - D725 Sanft-o-matic: first vac w/energy-saving electronic & "Max" switch, effectiveness (energy) of 23%, official seal for quietness and energy saving
1981 - D730 Logo-matic: first vac w/APC (Automatic Power Control), constant vacuum performance in relation to the fullness of the dust bag, effectiveness (energy) rate of 25%
1988 - D770 Lux Royal: first vac w/LCD and electronically integrated max/min switch, the "Can Do It All" Turbo-Clean!
1994 - D795 first vac w/9m (29 feet 6.331 inches)cable, HEPA filter