Audi remains secretive over how many laps it will be able to achieve between pitstops in this weekend's Le Mans 24 Hours.
The team has been keen to point out that the 3.7-litre engine in its new R18 prototype is a third smaller than its predecessor for only 10 per cent loss in power, but has refused to comment on the implications for fuel strategy.
Fuel mileage is crucial to success at Le Mans, since being able to do just one more lap between stops can mean, over the course of 24 hours, being able to complete the race with fewer stops.
Asked how many laps the R18 will be able to complete before refuelling, Audi technical director Ralf Juttner would not commit to a specific figure.
"We will drive until the tank is almost empty," said Juttner. "We don't know until we are at racing speed how long that will be."