I am curious to find out from any first hand sources if there really was a nationwide ignorance on the part of the Germans when they said after the war that they didn't know about the camps and purges. Did the Nazi government really hide it that well? Or did the Germans really know what was happening and wanted to cover up their guilt with the ignorance excuse.
A couple of threads that might help you:
How high ranking/connected did a WWII German soldier have to be, to know about the holocaust?
What did the German people know or understand about the Nazi concentration camps during WWII?
Although it's probable that lots of Germans didn't know about the gas chambers, most would have known about the deportations and the concentration camps. Keep in mind that the pure extermination camps were all in Poland. Still, inhabitants in German and non-German towns and cities would have watched Jews being marched to transports. Hilde Miekley's account of transport no. 18 from Berlin in August of 1942 implies something about German understanding of what was happening to the deported Jews:
"Unfortunately I have to say that many people stood in their doorways, expressing their joy at the sight of the forlorn Jews who were passing by. 'Look at the insolent Jews,' shouted one of the onlookers. 'They are still smiling, but this is the end of them.'" How Was It Humanly Possible? A Study of Perpetrators and Bystanders During the Holocaust
There was definitely knowledge of the executions of Jews on some scale. Train drivers/station workers had to deal with bodies on the train tracks, and witnessed shootings during the transports. A letter from a villager near Mauthausen camp in Austria (I'm assuming you're happy to include Austrians in your question?) wrote a letter to the authorities complaining about the regular executions at the camp:
"Inmates of the Mauthausen concentration camp are constantly being shot at the Vienna Ditch work site. Those who are badly struck still live for some time and lie next to the dead for hours and in some cases half a day." How Was It Humanly Possible? A Study of Perpetrators and Bystanders During the Holocaust
Anyway, only a couple of sources, which by no means reflect the knowledge of the wider population, but they do suggest a greater understanding of the fate of Jews by Germans than was originally believed after the war.