DJJ530, if you are still around, some further information for what it's worth....
Background: I have a rental for 16 days, late November, with Vamos, quoted $1003 including only the TPL coverage (7 passenger SUV). The best rate I have found elsewhere for the same dates, vehicle, and TPL direct from a provider has been Enterprise at $820.
I did some research with this 'http://rentalcars.com', and decided they are at least a legitimate business, and they offer free cancellation on rentals, so I went ahead and booked a 7 passenger SUV from them to find out what is really the deal. Research, for the sake of science (and Tripadvisor readers!). Figured if anything seemed not to my liking, I could just cancel.
I was booked by rentalcars.com at $506 for the same vehicle class and dates, through Avis. So, about half of Vamos cost, and a legit rental company. So far so good. Contacted Avis with my Avis confirmation number I received from rentalcars.com... Avis rep did indeed show the reservation in their system, for the right car, and said it did include liability coverage. Looking better by the minute! However, upon asking further questions about any required extra charges or coverages I would be required at the time of pickup, they pointed me to their website where they require an "ALI" ("Additional Liability") coverage if you are using credit card CDW instead of their products. No exceptions, no way around it, according to AVIS. This would be $19/day, or an extra $304, bringing my total to $810. I don't know if this is just their way of making up the $$ for people who use their own CDW, or what, but it changed the math on the whole thing. Now the rentalcars.com cost is within shouting distance of Vamos, and almost identical to direct-booking with Enterprise. Extra layers, extra things to go wrong, little savings. So, needless to say, the rentalcars.com one is promptly canceled.
Seems to be the normal case with 'something for nothing'; one is most likely to be getting a different 'something' than they expect, or to be paying in the end more 'nothing' than they thought. It may be possible to save a few dollars (emphasis on the 'few' part) via this rentalcars.com arrangement, but more likely it will end with a traveler starting day one of what should be a relaxing and enjoyable trip with frustration of one sort or another.
Edited: 6 years ago