I think that James May is why Top Gear works. Okay, it isn't that Jeremy Clarkson and Richard Hammond are unimportant to the process, but May is the smart one – he's the one who can make the bits of minutiae involved in how a flappy-paddle gearbox works (or doesn't) interesting. He is the one who can not just marvel at the history of motor vehicles, but explain it in a semi-concise and engaging way. May manages to be professor-ish without losing the ability to have fun (see his binge drinking with Oz Clarke on James May's Road Trip).
Enter James May's 20th Century in which, over the course of six episodes, May delivers to viewers the biggest technological advances of the past century. Episodes begin with May discussing something like how the world got smaller in the 20th Century and then delving into the various transportation and communication feats which made that happen, eventually reaching a conclusion about what he thinks the chief technology responsible for the shrinking of our world may have been.
Of course, it wouldn't be interesting to have May sit behind a desk and lecture, so instead he goes off and gets to fly in supersonic jets and drop Mini Coopers on huge sheets of glass to see if they break. He even gets to smash a few records (the outdated listening sort) and examine the latest artificial hearts. All of that may dampen the relatively educational aspects of the show, but they certainly keep the viewer tuned in. It is, after all, fun to see James going around in a G-force simulator, kind of like James Bond in Moonraker… except for the bit where May passes out.
Actually, as amusing as that particular moment is, the one which follows it turns into something of a disappointment. May has himself pass out (or nearly pass out) so that he can then explain why it happened and put on a pair of pants which help pressurize his legs and prevent him from passing out the next time he goes into the machine. In a later episode he explains the pants again as though we had never witnessed the G-force simulator moment. While the producers can't expect everyone to watch every episode, an acknowledgement that the same topic is coming up again not only would be nice for viewers, but would also alleviate fears that a whole bunch of segments were simply shot for the series and then pieced together later once someone worked out how to organize it into episodes.