A truly fascinating old book is "Two Roads To Africa" by a journalist on the weekly magazine, The Motor, Humfrey (correct spelling!) Symons, (or H.E. Symons), who wrote about his travels through the Sahara on various record breaking runs, including one to Timbuktu, another to Nairobi, and a long chapter taking a Wolseley to Cape Town on the first non-stop record run, in January 1939, which involved swimming across a river in the Congo after falling off a bridge, and getting a local jail to find 50 prisoners to go in and haul out the car...so they could carry on regardless. Well worth tracking down, particularly for the travel photos of the Sahara, descriptions of various places, maps and route information.
Symons "invented" the expansion tank idea for the radiator so expanding hot water was not blown onto the ground but collected in a container (with a run in a Morris it was a two gallon Shell petrol can). The book was first published in 1939, just before the war broke out, and is obtainable from the various sellers of second-hand motoring books.