For anyone who's ever wondered what kind of underthings Mark Webber wears, Porsche Motorsport has narrowed it down a bit for you by posting a photo of Mark in a rather see-through shirt. Mystery halfway solved: he's either a briefs or boxer-briefs man.
I mean, think of the extra drag floppy boxers create. I can't say I'm surprised here. Briefs or some long-legged variant thereof are clearly the most aerodynamic option for race car test day underpantsage.
Porsche will be racing their pair of 919s at the World Endurance Championship's season ender at Interlagos this weekend. The ultra-lightweight shirt is also serving an important purpose, as that particular part of Brazil tends to be muggy and warm this time of year.
For those of you who have been speculating about this underpants-related question for a long time:
b) I expect nothing short of a full wind tunnel analysis of boxers vs. briefs vs. boxer briefs in the comments, good sirs. You know what to do.