Bédélia cycle cars from early in the last century.
Powered, and I use the term advisedly, by one of these:
Located in such a way as to provide the nearest thing to a heater you were going to get. Only for the passenger mind.
Because the driver didn’t sit in this tandem design where you would expect
There was method to this seeming madness because the driver could in this case keep an eye on the casualty.
Here’s the single seat and cylinder one undressed. No, I haven’t a clue where the driver’s feet went. Note the friction dampers (the star shaped devices linked to the axles) and the wooden chassis.