The failure with STP-Paxton Turbocar at 1967 Indy 500, when the car retired from the lead just with four laps to go, did not stopped Andy Granatelli from further experiments. For his entries in the 1968 race, Granatelli’s STP-backed team commissioned Lotus to build a gas turbine-powered four-wheel-driven racing car. The Lotus 56, designed by Maurice Philippe, used a modified version of the Pratt & Whitney ST6 gas turbine used on the STP-Paxton Turbocar, developing now up to 600 hp. But the car itself was an entirely new and more advanced design which introduced a distinctive aerodynamic wedge-shaped body rather than a cigar-shape, in the year of the introduction of front and rear wings to F1. The car was first tested at Indianapolis by Jim Clark In March 1968. Sadly, Jim Clark was killed a few short weeks later at a Formula 2 race in Germany and never got to race the car.
Following Clark’s death at Hockenheim in early April 1968, Colin Chapman invited Mike Spence back to Lotus as part of their Indianapolis 500 team. During practice at the Indianapolis Motor Speedway on May 7, Spence was killed while testing one of four 56s built. The remaining three cars with Graham Hill, Joe Leonard, and Art Pollard were entered for the race, with Leonard claiming pole position. Hill’s car crashed, Pollard’s car broke down, while Leonard was leading with just a handful of laps to go when a fuel pump shaft failed.
|1968||USAC National Championship||Indianapolis 500|
|Joe Leonard||60||STP Corporation|
|Lotus 56||Turbine 4||STP Oli Treatment|