This is the critical set of questions regarding the scam the Mexican rental companies rely on to boost profits, and they know tourists will do little to effect a change.

While I am not certain what the Mexico legal minimum insurance is, that has nothing to do with the car rental company's "right" to conduct business legally yet unethically.

Just because the rental company follows the law, which says the rental company must provide some basic form of liability insurance, which they do, there is nothing to prevent them from saying the Supplemental liability policies are "Optional" and yet require you to buy them anyway.

HOW IS THIS LEGAL? Because in order for you to have the option to pay supplemental liability, you must prove you are either insured in another manner OR provide an extremely large security deposit to the rental company.

WHAT IS THE CATCH? The FIRST catch is that most or all the car rental companies do not "accept" 3rd party liability policies as evidence of insurance. That includes valid Mexico insurers. Even if their Terms and Conditions don't mention this, they will tell you of this policy at the counter. The SECOND catch is that the large security deposit is $20,000 on smaller cars and as of today, one policy requires $40,000 for larger cars and mini vans, and maybe more for luxury/specialty. THAT'S USD, not MX Pesos. Since most tourists don't have credit limits that high, it's unlikely they have any option but to pay for the "optional" liability or travel without a rental car.

The same can be true for the collision/damage insurance. The MX car rental companies are beginning to refuse to recognize coverage provided by credit card companies simply because you show them your credit card. They are requiring "proof" you have the coverage. And they might even refuse to recognize the "proof" since it's from a 3rd party, although so far everything I've read says they will not accept 3rd party liability insurance ... I believe though, it's only a matter of time before they also say they won't accept 3rd party collision insurance.

Having said that, this doesn't mean the 3rd party insurance is invalid. It doesn't matter what the rental companies accept or not, what matters is what happens if you need to use the insurance. Any valid 3rd party insurance will work correctly, more or less (meaning you might not anticipate shortcomings in your policy). The question is how do you successfully opt out of the "optional" insurance required by the rental company?

What I recommend:
- For your first time at any location in MX, with any car rental company you haven't been to in 2 months or less, contact a valid 3rd party insurer and start the paperwork BUT DONT BUY YET.
- If you are relying on your credit card company for CDW, print the policy out. Better yet, while I don't see quite how the AMEX CDW insurance plan is any better than the basic coverage on any credit card for CDW, AMEX offers a fee based CDW policy of about $16 to $25 per rental period, up to 30 days (some vehicle exclusions apply, but similar to the basic credit card coverage). They give you a policy and the policy works and you are charged automatically when you use the subject credit card for your rental.
- Assuming you win the battle with the rental company because you have a credit card with a credit limit high enough to accommodate the $20,000 or $40,000 USD security deposit for liability, immediately call the 3rd party insurer to pay and begin the liability policy. I recommend this because if you buy the policy before hand, then are forced to buy the "optional" liability coverage, the 3rd party ins co will not give you a refund.

What if all that fails?
- This might not help, but I recommend making reservations with more than one car rental company where you don't need to pay anything up front. Try making 3 reservations. Walk out of the first one and see if they let you go. Maybe make a bit of an effort to change their minds, but don't waste too much of your time. Go to the second one and try again. Here's where you will need to be committed. If it's the same, maybe you have to bite the bullet and just eat the extra money. Or you might take one more shot to walk out and go to your final place and make at least a small effort before paying for everything.
- I'm planning on also knowing where the public transportations is. After all, depending on where and how your trip will be, public transportation, even with some taxi fees, could cost a lot less than renting the car with all the required add-ons
- Last but not least, if you are going to a resort where you might spend 1/3 to 1/2 your days not leaving the resort, or using tours to explore, NOT RENTING AT THE AIRPORT could give you a lot of "car money" to spend on the transfer from airport to resort and back, plus 1-3 single day car rentals directly from or near the resort. Just a thought ...