Explain the cruel comparison Rasheed makes for both Mariam and Laila. How does Rasheed use this to his advantage?

Rasheed reveals to Laila that Mariam is a harami and compares her to a trusty Volga automobile. However, Rasheed equates Mariam to a Mercedes Benz - one that requires special care. Rasheed holds Laila in higher regard because she is younger, beautiful, and smart. He, however, finds Laila more temperamental than and not as submissive as Mariam. He uses this comparison in an attempt to keep both women in line.