In California a a DUI can be enhanced for many reasons, excessive blood alcohol, priors, refusal and perhaps the most severe, the dreaded speed enhancement. The speed of the vehicle can add 60 days or more to a sentence.
If the DA alleges that you were driving 20 miles above the speed limit on a city street or 30 mph above the limit on the freeway and the speed was reckless than the Court can impose a 60 day jail sentence, even on a first offense.
This punishment can be avoided through negotiation however and it is not mandatory, so it is important to consult a lawyer to discuss your options. Kern County does not often allege the enhancement but can overlook the penalty.