The line from Madrid towards Extremadura (Cáceres, Badajoz). Mostly units now, but one diesel-hauled Talgo a day left.
The section from Plasencia onwards will be electric very soon, but the part from Madrid to there will stay diesel for some years, since electrification was only recently announced.
However, I suspect that single Talgo will be replaced by class 730 very soon.
The single daily Intercity from Madrid to Almería is also a diesel-hauled Talgo throughout, but runs under the wires for the first half of its journey.
Isn't Granada also DMU-operated? I went there some years ago, didn't get close to the station but saw it from a distance and it looked like some kind of DMU was in the platform. Not sure if this operated to/from Madrid though.