ask him how many miles he has on his "first delivery in the nation" 5BW, and how many miles he has on his commoner 4BW and that should tell you the answer to your question.
But is it because he cherishes his 5BW so much more than the 4BW that he's preserving it, or does he enjoy driving the 4BW so much more than the 5BW that he can't help it?