The Lotus 56 was designed by Maurice Philippe as Lotus 1968 entry in the Indianapolis 500, replacing the successful Lotus 38. Based on Parnelli Jones' STP Granatelli turbine car ("Silent Sam") that almost won in 1967, Colin Chapman's team again produced an even more innovative design. The 56 was shaped like a wedge on wheels, in the same vein as the later Lotus 72, which was also designed by Philippe (who had replaced Len Terry, the designer of previous Lotus Indy 500 cars)[1] and Chapman. The engine of the 56 was also noteworthy, as it was a Pratt & Whitney gas turbine engine of over 500 bhp (370 kW) and 1560 nm (1150.44 lb/ft) . To get the best out of the power produced, the 56 was fitted with four wheel drive, something also used on the Lotus 63 without success. Jim Clark was enthused about the car in testing, but he was tragically killed in an F2 Lotus 48 in April 1968 before he could qualify the car at Indy - an occasion in which Mike Spence died in the 56, adding more tragedy to Team Lotus. Nevertheless, Graham Hill, Joe Leonard, and Art Pollard were entered for the race, with Leonard claiming pole position. In the race Leonard was leading with ease with just a handful of laps to go when the engine failed. Lotus' innovation incurred the wrath of the governing body of American motorsport, and USAC deemed turbine cars and four wheel drive illegal shortly after, much to Chapman's frustration. The 56 would not be a total loss in any event. It inspired the Formula Ford 61 and, in combination with wings (pioneered by the 49), would transform Formula One

56B
 

A 56B car was made in an attempt to rectify the problem of the Type 56. The car had a revised bolbous wedge shaped body work, to accommodate larger fuel tanks and the Pratt & Whitney STN6-74 PT6 turboprop engine. The car was competatively unsuccessful.