Any current or retired car guy (especially old F&I mgrs) will advise you to avoid any "mechanical break-down insurance" policy. They are not a real warranty.
If the manufacturer does not offer extended coverage, you are better off not buying anything. If you are worried about breakdowns, then put some cash aside in an interest bearing account for unexpected repairs.
Note: I purchased additional Factory-UnderWritten Coverage for my Toyota FJ Cruiser. At 96,000 miles it needed an inner transfer box seal. The Toyota dealer in Rexburg Idaho replaced it and did a couple of other warranty repairs. All day teardown and reassembly.
Repair order total $3400.00 and change. My cost was the 450.00 I paid for the Warranty Coverage. Money well-spent!
Let me add that there is a Very Wide Profit Margin built in to the quoted prices of warranties and "Mechanical Breakdown Insurance, meaning that you should be able to finagle a better price if you are willing to grind on the dealer selling it.
The dealer cost of both types are based on Frequency of Repair actuarial data. So if you are buying a Jeep , the dealer cost is staggering, because Jeep Knows those vehicles will break. On the other hand Honda and Toyotas factory warranties have much lower dealer cost, because they don't break as much, Simple.
As I said there is a big difference between factory coverage and "insurance" sold by 3rd party sellers. You may find that one of the 3rd party companies is legit, but if you purchase 3rd party Mechanical Breakdown Insurance, it will never be the same as the coverage offered by the manufacturer. Believe me.
Sure, you might have a good experience, but insurance companies make money the old fashioned way, by denying claims as a policy.
Insurance is regulated state by state, so the coverage limitations will be variable on that basis as well.
Before you buy anything Other than Factory coverage, do your homework on the company that is Under-Writing it. You will be glad you did.
Plenty of Info online Warranty VS MBI
https://goo.gl/3QrWC7