Cheapest place/method to rent a car, and WHY.

[BTDretire]

I rented from Budget. The time was 8 days, I listed an additional driver.
 Total cost was $310.
 Starting price was $149.99 + $13.00 for the additional day.
 $65.00 to list my daughter as a driver, but that doesn't include taxes and
additional fees.
 I haven't got the bill for an unknown to me bridge toll where they apparently take
the license plate picture and send the bill. That's an additional $19.99 plus the cost of the toll.
 Oh, if you don't refill the tank, they will at $9.98 a gallon. I did refill.
 Anyway--- Next time I rent a car, what is the best deal?
 

[ketchup]

It varies drastically.  I've had Alamo, Hertz, Enterprise, and Budget all come out as cheapest depending on where I am renting.

The most expensive option is always at an airport.  Least expensive is based almost entirely on demand.  If flying into an airport and renting a car, it can be worth it if timing allows to Uber to a nearby off-airport location.

It costs more in the summer than the winter.  Sometimes a lot more.

It's usually cheaper to book in advance.  Not always.  Sometimes there's a token discount for paying in advance.  Don't do it.  I don't give them a cent until they have a car for me (Jerry Seinfeld can tell you how a car rental reservation really isn't always a reservation).  You also usually lose all ability to cancel or change your reservation.  It's not worth it.

Many "memberships" offer discounts and/or waive fees.  AAA waives the young driver/additional driver fee at Hertz (saves big $$ if under 25; though I'm not anymore).  Marriott's loyalty program does something similar.  Promo codes are all over the place (sometimes they outdo membership discounts).

Many fancy-ish credit cards have rental car damage coverage built in (so you don't have to buy the rental place's insurance).  I use a Chase Sapphire Preferred.

Cheapest I've run into is Hertz in the Chicago burbs away from an airport in the middle of winter with AAA discount.  I think it was $14/day for two days (including taxes/fees), and we drove the car something silly like 1000 miles in those two days.  Next cheapest was $104/week one time, similar situation.  Most expensive was Alamo (the cheapest option) for just over a week out of the Portland airport (I think it was ~$370 altogether).

[JanF]

Costco waives the 2nd driver fee. The best method of getting the cheapest rate is to keep checking the rates to see if it drops...sometimes I use https://www.autoslash.com/ for this.
As ketchup said, airport pick up is the most expensive bc they tack on an airport fee. Compare the rate between airport pick up and rental place near where you're staying, it might be worth it to switch. Plus some hotels have free airport pick up/drop off and most of the time people rarely use their cars on the first/last day of travel so there's room to save on 1 or 2 days of rental there.

[seattlecyclone]

Hotwire.com often offers cheaper last-minute deals where they don't even tell you which company you're renting from until you've paid. I haven't always experienced the greatest customer service when I've done this, but it does cost less.

[HipGnosis]

Most cities have 'rent-a-wreck' (or something like it).  They're cheap.

[BTDretire]

 And to add to my $310 bill, today I received a red light camera bill from Budget for $60 plus $30 more for handling fee.
 Running red lights is not something I do, so I'm a little concerned, and I'm trying to get the pictures. Not saying I didn't do it, but I want to see the pictures.
 They weren't open to give me some info I need for the website, but I'll see tomorrow.
 oooooohhhhhmmmm, oooooooohhhhmmmm.

[Goldielocks]

Your base rate looks very good.   

Next time, the key is to get a Budget membership card so you can add a second driver for free or reduced money.  (I don't know about budget, but two of the others does this). 

Others have suggested using insurance on your credit card.  This usually covers any vehicle damage, but check your coverage statement.   Often the state usually requires you to carry liability (people) damage through the rental company, but sometimes your personal car insurance can extend to rental cars, for a very low fee per year.

Don't get traffic tickets, even if it is only $60 for a ticket (what magical state is this?).  I find that the toll handling charges range from usurious, to acceptable and it depends on city.  San Francisco and Toronto they were acceptable -- one fee for the entire week that included multiple tolls and an electronic toll transponder.  I think it was Florida where I was hit with a handling charge for each toll.   Shop around and call the counter where you will be renting to ask specifics ahead of time.

Always plan ahead where you will refuel upon your return.  Some fueling stations are 15 minute drive away, or behind construction.