Europeans can be racist toward other Europeans. A lot of people in the US consider a European a European, one people group. Europeans have another views. Just goes to show race is a social construct, and not a genetic one. You could theoretically mince races down so much that each immediate family--or even each person--was there own race.
The Volga Germans resisted assimilation as much as they could. But Part from their language, they are--the ones I observed--more German than many modern Germans. As for the Turks, I think they are about as assimilated as African Americans are into white culture.