Second banana Jim Earl from the Marc Maron Show has an on-going infatuation with steam-powered cars. At first I didn't buy his enthusiasm, but from Bouphonia, news that novel potentially steam-friendly designs have started to surface, including the Quasiturbine, the StarRotor, and the RandCam. Similar to the traditional Wankel rotary engine, these will in all likelihood suffer from rotor seal problems until "they" get the kinks worked out.
On the plus side, rotors generate little vibration and can operate under lower pressure, making for a smooth ride. Thanks also Phila, for unearthing this timeless gem from Bruce McCall: