The CDU/CSU-SPD government was pretty even as far as I know, despite CDU/CSU being much bigger than the SPD. The SPD got their way on a lot of social welfare policies including the minimum wage (something CDU/CSU mostly opposed), while CDU/CSU were able to block tax increases on higher earners (something the SPD promised during the 2013 elections).
That's alot to do with Merkel though, as much as the SPD, and her own tactic on realising when a policy is popular with the public and stealing it from the party that originally proposed it. The minimum wage and nuclear power are classic examples of her moving into the SPD and Greens' territory respectively
