In Britain only 2,000 cars cars were made in 1940 and by 1945, it was 17,000 units. The latter figure was more than I thought (due to 'you know what' was going on). By 1946, 219,000 cars were made and things moved quickly thereafter, as can be seen below:
British production peaked in 1972, with 1,921,000. Then, poor management and worker unrest derailed the industry. Within ten years, production dropped to 888,000 or less than half! What a disaster. Things improved when Rover teamed up with Honda and the Japanese found British workers to their liking and invested in plants. Even BMW's monumental stuff up of previously profitable MGR could not stop the UK car making industry from prospering. Unfortunately, the recent world economic slow down hurt UK production rather badly. It is now coming back again in 2011, but the 2010 figure was disappointing.
As I see it: A classic case of could have been, but isn't. Still, it could be much worse...like no car industry.