Alaco is a Los Angeles petroleum company featured in L.A. Noire with several gas stations located across the city. Tanker trucks are also seen bearing the Alaco logo. A billboard can be seen of the companies name in the scene where you investigate the car registered to Adrian Black in the case "The Driver's Seat."
The street crime Cosmic Rays takes place at the Alaco station at the corner of Wilshire and Flower.
It is quite obviously an imitation of Texaco, and the name Alaco probably implies Alabama instead of Texas.