Brian
You're getting you history a bit mixed up. The maximum effect of the great depression hit Germany very, very hard causing hyper-inflation, runs on the banks, etc., in 1931. Hitler didn't come into power until August 1934. The great depression and the distrust in the existing Weimar Republic that it engendered in the German people was one of the reasons that Hitler came to power. He promised to sort it out, and they believed him, and in a way, I suppose you could say that he did - pity about the 60 million premature deaths his 'sorting out' triggered.
Oh, and the autobahns - he had those built to enable raid troop movements.
Mike