The IMSA SportsCar Championship underwent a profound shift with its adoption of new rules for 2023. Teams now had a spec hybrid system to optimise, while the move from DPi to LMDh (known Stateside as GTP) also meant a new philosophy for calculating energy usage – falling in line with the World Endurance Championship, allowing for the platform to be equalised against Le Mans Hypercars.
The consequence of stretching a tank of fuel too far is unchanged. But no longer is stint length dictated entirely by fuel numbers. Instead, the primary concern is now how a car uses energy from a virtual tank – think of it as a combination of fuel used by the internal combustion engine and torque produced by the hybrid system – measured by sensors attached to the rear axle (or both axles for LMH cars). The importance to the rulemakers of tracking the so-called Maximum Stint Energy (entirely separate to the actual fuel load) was underlined at the WEC’s 6 Hours of Portimao, where the #7 Toyota was heavily delayed while a malfunctioning torque sensor was fixed.
