The three manufacturers that will slug it out for this season's World Endurance Championship titles are back on the grid at the Silverstone opener this weekend with new or nearly-new cars.
They have each undertaken significant development programmes for the new season: Porsche has built an all-new version of the 919 Hybrid; and Audi and Toyota have undertaken significant upgrades of their respective R18 e-tron quattro and TS040 HYBRID challengers.
Their only meeting so far, at last month's WEC official test at Paul Ricard, provided no clear conclusion on who has gained the most - which will make the events of Silverstone this weekend all the more intriguing.