I can see power steering
Sex drive when you swerve, I want that interference
It's coherent, I can hear it, mmhmm

from Kendrick Lamar (Ft. Drake) – Poetic Justice Lyrics on Rap Genius

Meaning

Power steering = troubles
Sex drive when she swerves = Horny girl when she drinks Interference = He wants to take care of the troubles

The girl is troubled and resorts to alcohol as a solution, but Kendrick believes he’s all she needs.

Or

The way she rides the D, it’s like she’s power steering it. She “swerves” or i.e. she can ride a mean dick.

Her interfering signals (moans) are clear.

In physics, waves that are coherent, i.e. have the same frequency, direction, etc. interfere in a way that actually amplifies the resultant wave.
So he is perfectly in tune with her and their interactions create something larger than the both of them.

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