San Francisco Bay Area bridge tolls, using a rental car

The Golden Gate is $10, the Bay Bridge and others in the area are $8 and it allows you to go over and back. $125 is quite a bit to prepay. As suggested, register the rental car license plate on line so the bill comes to you. Last time we were down there it took several weeks to receive the bill for the Bay Bridge followed by one for the Carquinez Bridge.

Do I have to register the car as suggested? Won’t the rental company agree to just bill me for the bridge crossings?

The rental car companies usually charge an additional service fee. Of course, you can always pay for toll coverage, but it's a daily charge, for every day you have the car.
My experience is for the Golden Gate, and we usually pay online within 24 hours of crossing. Usually there are signs with the website, or you can just google the site. For the GG, you only pay for the south bound crossing. Enjoy the scenery!

Ask your rental agency if a toll transponder comes with the car. I just rented a car in Maine and didn't know to ask that question, because there are no tolls where I live. It turned out the car was equipped with a transponder for the "EZ Pass" lanes.

I rented with National. The charge for the transponder was $4.95/day, plus whatever tolls I incurred which will be billed later. Tolls were not mentioned when I made the reservation, so it was not something I could opt out of, but I also wasn't asked to pre-pay. I would not pre-pay $125 for tolls!

If the rental does not include a transponder, I guess I would find out what the fees are for Avis to bill you for the tolls. If it's more if you don't pre-pay - well, at that point I would find another rental agency.

It makes sense to register with fastrak as suggested above. It seems the least expensive way to take care of the tolls. I just didn’t realize that you could register a rental car. I guess when you return the car you unregister it soon after you return the car.

The toll registration is time-based, so it automatically expires at the date and time you specify. No need to do it manually. The rental-car toll fee is a ripoff (IMHO), since you’re charged the daily fee whether you use a toll bridge (or lane; there are Fastrak lanes all over the Bay Area now) that day or not.

For extra peace of mind, you can register the car ahead of time, once you know its plate number.

Thanks so much everyone! We had our trip to the San Francisco Bay area, and though the car rental tried to keep it a secret, Leonard told me about signing up on Fastrak to have our tolls for our rental car charged to the website. It worked great! Saved us maybe $200.