The short answer is no! Auto accidents which occur in Mexico are subject to the laws of the Mexican government. An automobile accident in Mexico is considered a criminal offence as well as a civil matter. Under Mexican Law you are required to have valid automobile insurance; a US policy is not valid in Mexico. If you happen to find yourself involved in an accident you could face harsh consequences including jail time, even if the accident is not your fault.
My auto insurance policy covers me 25 miles into Mexico and I only drive to Tijuana!
Americans have a tendency to think that their policies will cover them up to 25 miles into Mexico. However, the liability coverage offered would only apply if you were involved in an accident with a Non Mexican resident or citizen and the suit was brought against you in the United States. In addition many insurance carriers will also require that you have a Mexican insurance policy in force at the time of the accident. The physical damage (comprehensive and collision) may be covered but only for the limited miles. You would also need a police report which may be difficult considering the possibility of a language barrier.
To play it safe assume that your auto insurance coverage ends when you enter Mexico. There are several Mexican insurance policies that can be purchased while you are still in San Diego County.