Best for multi-day trips in the US and Canada
Turo is the "Airbnb of cars" where regular people rent out their cars since they're usually not being used. It's the best option when traveling since they focus on longer duration, multi-day trips where people need to go further. They're in over 4,500+ cities across the US and Canada which includes airport pick up so you can bypass the line at a typical rental counter, pick up a car, and go. Furthermore, with such a big variety of cars it can be a better value than traditional rental cars or you can get a much cooler car, like this McLaren or Tesla. Ya ain't gonna to find those at Hertz.
Many credit card companies, however, don't recognize Turo as a valid car rental service so you can't use the additional insurance these cards offer. Check with yours. The coordination with the car owners can sometimes be tricky too (but that's true of all peer-to-peer marketplaces).
Best traditional car rental search
If you prefer the traditional car rental approach, there are dozens of them: big ones like Hertz, Avis, Enterprise, etc but also smaller regional ones. Rentalcars.com searches lots of them for you at once and can generally get you good deals.
- Once you find a few leads, check the car rental service directly to make sure you're indeed getting the best deal
- Rental car bookings are usually cancellable all the way until you pick up the car, so no harm in locking in a good rate ahead of time
- After reserving, use with AutoSlash (mentioned below) to check for price decreases
For receiving alerts if your rental's price drops
You can usually cancel a traditional car rental reservation anytime up until you show up at the counter. This means you're free to comparison shop all the way until then and rebook if you find a better deal. Too lazy? Let AutoSlash do it for you. Just give it your car rental booking info and it'll automatically email you if they find a better price for a similar booking. Many report considerable savings without much effort.
An honest car rental search (Europe only for now)
Renting a car can quickly get complicated with random hidden fees, credit card holds, insurance requirements, and more. MyTripCar is a new car rental search that shows you all of these hidden costs up front before you rent in what they call the final price. No other car rental searches today do that.
They're currently Europe only and only have a few rental partners so not a truly useful tool yet for global travelers, but we like their "do right by the customer" approach and thought they were worth mentioning in the hopes they grow to more regions.
Great for short trips within cities
If you're traveling to a city and prefer to drive yourself for short trips (think minutes/hours), we recommend car2go. It's a modern take on city carsharing that uses GPS to let you pick up and drop off cars anywhere with the entire process from beginning to end done through a mobile app. No human interaction needed. Since it's the brainchild of Daimler, the maker of Mercedes Benz, you also get access to some cool cars like the CLA. Prices are cheap enough it won't be far from what you'd pay for an Uber/Lyft (not to mention there's no surge pricing).
car2go is currently in 27 cities across US, Canada, Europe, and China with more to time. Zipcar is your best option otherwise since they're in hundreds of cities and airports, but they have a monthly membership fee which can be a no go if you're only there for travel (although the membership gets you access everywhere).