Some cars leave a paper trail; the Lotus 56 left a name and a place in Lotus's list. What follows is what can be said with a source behind it. Its designer of record is Colin Chapman / Maurice Philippe.
Where it came from
The Lotus 56 was a gas turbine-powered four-wheel-driven racing car, designed by Maurice Philippe as Team Lotus's STP-backed entry in the 1968 Indianapolis 500. All three cars entered and retired from the race with Joe Leonard's car expiring while leading just eight laps from the finish.
A variant designated the Lotus 56B was entered in three races in the 1971 Formula One season but with little success. The 4WD concept was also used in the 1969 Lotus 63 F1 car, and the wedge shape became a prominent feature of the world-championship-winning Lotus 72.
Under the skin
it is rated at 500-600 hp. Kerb weight is 612kg. Power-to-weight lands near 817 horsepower per tonne, which is hypercar territory, where the limiting factor is the tyre, not the engine. These are manufacturer figures carried by Wikipedia and Wikidata, not road-test measurements.
In context
Where it sits in Lotus's history is not in doubt: the 72 (F1) / 42 (USAC IndyCar) came before it; the 72 (F1) / 64 (USAC IndyCar) followed it. Nearby in the Lotus catalogue sit the Lotus 100T and the Lotus 101.