The three or more prior drunk driving convictions that elevate a Veh. C. §23152 offense to a felony under Veh. C. §23550 must be pled and proved at the preliminary examination.
In People v. Superior Court (Mendella) (1983) 33 C3d 754, 191 CR 1, the California Supreme Court held that sentence enhancements must be pled and proved at a preliminary examination, or they are subject to challenge via a Pen. C. §995 motion in Superior Court. However, in People v. Wims (1995) 10 C4th 293, 41 CR2d 241, Justice Kennard remarked at footnote 5 of her concurring and dissenting opinion that Mendella does not apply to prior convictions, and this seems to be an accurate statement of the law.
But drunk driving convictions are not alleged as sentence enhancements in §23550 prosecutions, but rather as offense elevators (see, People v. Coronado (1995) 12 C4th 145, 48 CR2d 77); they elevate the §23152 offense to a felony. Thus, they are subject to Mendella. Miranda v. Superior Court (1995) 38 CA4th 902, 45 CR2d 498, the only case that mentions both Mendella and Veh. C. §23175 (now Veh. C. §23550), is in accord. See also, Panos v. Superior Court (1984) 156 CA3d 626, 203 CR 115.
Similar reasoning applies to Veh. C. §23550.5 felony drunk driving prosecutions.

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