I recently had some work done on my car by a "small time mechanic" who does not provide loaner vehicles. I saved lots of money by using this mechanic, so it was worth it to rent a car during the time my vehicle was in the shop.
For the first time, I tried Turo. Uber calls itself car sharing, but this is real car sharing. You have individuals that rent their own personal cars through the Turo platform.
Initially I wanted to rent a car for 3 days. I was quoted $281 from National Car rental for the airport - which was a $30 Uber ride away. Seemed like a bit much for a car I was going to use to commute to work and/or a grocery store. I tried using some aggregators and found the cheapest was $47/day - still cheaper than National.
I ended up signing up for and reserving a car (a nice 2014 Kia Soul) at 4PM on a Sunday and took possession of the car 3 hours later at 7:30PM. I was charged $115 for the 3 days - which is pretty competitive for a major cities during the week. Add on the fact that the owner of the car picked me up at my mechanic for free!
I will be using Turo in the future. Evidently it can be used all over the US in major cities. Here is my referral link - disclosure: I get $25 credit if you sign up using my link.