Legal Question in Civil Litigation in California

In California, the seller is responsible for ensuring the vehicle is smogged and passes smog.

When the seller assured you that the car would pass a smog inspection, the seller was making an "express warranty." If the seller put it in writing, you are in great shape. If you can't get a refund of your purchase price, you can sue the seller in court. If your sale agreement with the seller was oral, rather than written, and the car was more than $500, you can still sue the seller, as long as the seller does not deny that a contract was ever made. If the car was less than $500, you can sue, even if the seller denies the contract was made.

Your damages (i.e. what you can sue for) could be the cost of fixing the car to the point where it should have been, at the time of sale plus, if you lose the car's use while it's being repaired, you can recover the value of the loss of usage. Generally, loss of use is valued at the value of renting a similar car.