So lets stop to consider, regardless of that nazi memorabilia.
You live under a fascist dictatorial regime. There are very few options available for you to live a relatively uneventful life.
Either you're an open, true, supporter, a passive one or a dissimulated dicident. Yes, there are more options available, but lets take these as the most broad categories.
Now let us consider that your regime an enacted several acts of domestic, unprovoked violence, internal purges and other assorted brutal and unpredictable actions against social peace and stability, in order to cement its unquestionable power over an entire nation.
Then, that same regime advances to a state of war, where all resources and infrastructure are comandeered to bolster the military.
At some point, companies are put a very simple option: either they cooperate and remain active or they refuse and suffer the consequences, that at best can be simple nationalization and purge of the heads.
Considering all of this, BMW supporting Germany's war effort is understanble.
Do I agree with that decision? No. But do I understand it? Yes.
Cooperate and live or refuse and die? Not an hard choice, especially if a lot of money is put on the table.