The Anatomy & Development of the Sports Prototype Racing Car

Truth in 24 - when Audi commissioned NFL Films to make a documentary about their foray into diesel engines at Le Mans. Not super technical, but definitely shows the extent to which a team goes to get any and all competitive advantages. And not a documentary, but any book by Ian Bamsey is worth a read. He's the founding editor of Racecar Engineering magazine and has written a number of approachable yet very technical books on the development of race cars. My personal favorite is The Anatomy and Development of the Sports Prototype Racing Car which covers basically the entire technical history of Group C.