BMW is a good example of a company that started small, making aero engines. Their first big dip saw them effectively surviving by making pneumatic brakes under licence, with the market for aero engines and German ones at that having been hit by WWI.

Motorcycles came along in 1924, rapidly proving a big success. Then in the late 20s, they branched out by manufacturing Austin Sevens under licence from Austin in the UK as Dixis. Increasing German input saw them develop a strong range of sporting cars and winning the Mille Miglia with the 328.

This was then punctuated by WWII and a ban on manufacturing cars and motorbikes that BMW this time survived by making bicycles and kitchen utensils. Yes, they kept going by making pots and pans!

When car production resumed, they were stuck with large and expensive models from 501 to 507 and these didn't provide enough volume, so again they went a licencing route and also built Isettas - so a range consisting of bubble cars and sporting saloons, coupés and convertibles with straight sixes and V8s. Not really a sustainable model and they came within a hair's breadth of being merged with Daimler Benz in 1959. It would hardly have been a merger of equals and unlikely to have sustained the BMW brand alongside Mercedes, so probably would have been the end of the story.

The turnaround came with the "Neue Klasse" models introduced from 1962. Volume increased more or less annually from then on and now BMW are one of the leading "premium" manufacturers and also one of the most profitable. A couple of wrong turns along the way, like the acquisition of Rover, but it's been pretty much up since the 60s.