A 24-hour battle of speed and EFFICIENCY

At Le Mans this month, amped-up hybrid prototypes from Audi and Toyota face a revamped Porsche 919 while Ford hopes to recapture glory with its new GT-R.

World endurance racing at Le Mans is no longer only about who finishes first after a grueling 24 hours, but also about winning with the greatest energy efficiency. For 2016, the Federation Internationale de L'Automobile (FIA) has tightened the fuel allowance for the top-echelon Le Mans Prototype 1 (LMP1) category in an attempt to further link racing and efficiency-and as an attempt to arrest the stunning increases in speed seen during 2015.

This year, the fuel allowed per lap has been reduced by 10%, for an approximate reduction in energy per lap of about 10 megajoules (2.77 kW·h). Peak instantaneous fuel flow also is reduced by 10%.