So recently, I had discovered the service called Turo (formerly RelayRides). Basically it is like Airbnb, but for cars! People rent out their personal vehicles and you can choose from some interesting vehicles. I ended up with a manual mini cooper S with leaking oil and bald tires, but it was still fun and worth it. Anyways, they just added a transmission choice to the search options! So I will definitely be researching my next trip on there.