It's often hard for me to put my finger on what makes it perhaps the least Russian of the books that I've read in Russian literature. It could be, perhaps, the fact that it talks about universal ideas in a very universal way, not making any case for Russian exceptionalism, so to speak. Tolstoy was big on Russian exceptionalism (particularly when talking about peasants), Dostoevsky thought that Russian faith was endowed with unique and world-saving properties, Pushkin poked fun at Russian quirks, Chekhov did the same, etc. Turgenev does none of that, at least not in a way that makes his novels seem Russian. They could just as easily have taken place in England, for example. I would say it was because they were written in France, but Gogol wrote Dead Souls primarily in Italy.