x1 is an omnibus for carrying x2 in medium x3 propelled by x4.
Cf. sorprekarce; pavloibasfa for single-decker, relyloibasfa for double-decker jonbasfa for articulated, clajonbasfa for bi-articulated, dizbasfa for low-floor, drucaubasfa for open top, kumbasfa for coach, dicybasfa for trolleybus.