The cost of insurance, gas, and crazy insurance deductibles makes renting a car in San Jose a pricey proposition. I used to rent a car almost every trip, but I've noticed that strictly using taxis, I spend only about 1/3 of what I do when renting.
Plus, the rental rates during the high season are insane. They are charging $80/day for a small SUV

, compared to $35-42 during the low season.
I agree with the others, use taxis. Even if I was going out of town, I'd use Interbus over rental cars. It's a very cost-effective option. And there's no worrying about accidents, thugs puncturing your tires, then robbing you when you stop, petty theft, cosmetic damage which is only covered at 80% (unless you pay even more for total protection).
I had an accident once. Luckily, the other driver admitted losing control at the scene, and they did not go after me for the damage to his piece of shit pickup, and my credit card paid for the damage to my rental. So it didn't cost me a penny out of pocket. Well that's not true.... They did charge me for half a tank of gas because when they hauled away the damaged car, the tank was only half full.

I should have told the tow truck to stop at the Texaco on the way to the rent-a-car place.

I made a big fuss and the only charge me $24, instead of $48.