Trolley bus converted to diesel power and used to de-ice the overhead wires in the winter. It was used as a hybrid passenger bus and de-icing vehicle from the late 80s to sometime in the 90s, then exclusively for de-icing until a special de-icing truck was acquired in the 2000s.
1993 FAW Cycler SKL160. Powered by a 250cc engine with a top speed of 80 km/h (50 mph), designed for a then-typical Chinese family of three under the one-child policy, and was to be priced under US$3500. It never got past the prototype stage.
Breda dual-mode trolleybus. Italian articulated transit bus built exclusively for Seattle from the late 80s/early 90s, housing both a conventional diesel drivetrain and electric trolley drivetrain that shared a set of controls but were otherwise separate.