The Miranda Rights Admonition is usually voluntary in San Diego & California DUI cases and not usually given, for the following reasons: During the investigative stage, the officer has no obligation to advise one of the person of  Miranda rights (to an attorney, to remain silent).

In DUI cases, the officer asks all the questions before arresting (handcuffing), thereby avoiding the issue of having to advise.  The person does not have to answer any questions by the officer but the person usually does.
Not until handcuffed is the need for the Admonition triggered.
And by that time, the DUI officer normally has all the answers to all the questions needed to arrest for Driving under the influence of alcohol and/or drugs.
After that, the officer often abstains from questioning during custody.
It is not like the officer takes the person downtown and puts them under a hot light:  “Did you commit a DUI?”
In DUI cases, the person has no right to speak to an attorney before deciding whether to take the required breath or blood test (it’s called California’s “implied consent” law when one signs up for one’s license).
In sum, the right to remain silent and the right to an attorney are substantially different in a DUI case.

Exception:  Nonetheless, any interrogating statements made after taken into custody (for example, in the police car:  “Were you drunk?”  “Yes I was very drunk”) may not be used against the person at trial and are subject to suppression for failure to admonish.