I have a method for saving money on car rentals that's a bit cumbersome but has worked for me. Now a new website promises to automate my clunky old process.

My method is tested and proven. When I book my flight weeks or months before the actual date of travel, I also book my car rental at the same time. Then a week before my travel date, I reshop the car rental rate. At least 90% of the time, I find that I can book a new car cheaper at the last minute, so I just let my old reservation go.

For example, my family and I took a ski trip in December and we needed to rent a car. My price went from just under $300 when I booked the flight to just under $100 including all junk fees when I re-shopped the rate a week before travel.

But there's a new website called AutoSlash.com that automates my process. AutoSlash keeps re-shopping your rate for you every single day after you book. The company claims that 85% of the time they'll end up saving you money.

A New York Times reporter tried out the service and agrees with the company line. He wrote, "It's enough to make AutoSlash my first and only stop for auto rental booking."

That assessment is a bit overboard for my taste, but you should still check this site out when you need to take a trip and rent a car.