Costa Mesa (SNA/LAX) to Santa Clara (SJC)
Cheapest, but absolutely miserable. Assumes showering at a gym.
Cheaper flights, but factor in LAX traffic and expensive parking.
Tough commute, but you get a stable base to leave your belongings.
Brutal ~12.0 hrs driving/trip. Assumes $286 round trip (gas+dep).
Most convenient long-term. Leave your clothes and monitor in NorCal.
Easiest commute. Southwest out of John Wayne, sleep in a hotel.
If you choose to drive ~3,120 miles a month (780 miles/week), you will rack up ~37,000 miles a year. Even in a highly efficient, reliable car like a newer Civic or Prius, this heavily depreciates the vehicle and increases maintenance frequency (tires, oil, brakes).
While sleeping in your car looks cheapest on paper, the physical toll, lack of deep sleep, and loss of 48+ hours of your life to the I-5 every month usually makes Flying out of SNA + Hotel or Flying out of SNA + Renting a Room the only sustainable options long-term.