IMHO calling it a warranty is a misnomer. As you said in the first sentence of your post, it's really a pre-paid service contract, and what they'll fix and under what conditions will be determined by the terms of your contract. So read it very closely and make sure you understand your coverage, exclusions, conditions (such as payment of a deductible, where you can/must have the work performed, whether you have to obtain pre-approval from the company, etc.), and the track record of the company.
I have purchased extended warranties as the original warranty was expiring, typically 36/36. I have only purchased the manufacturer's warranty of the brand of car. I have never purchased from my selling dealer of the car. I have gone online, search for low cost extended warranty from that manufacturer. You'll find forums that discuss the subject. There are dealers around the country that deal in extended warranty volume, selling across the country. I send in their request for a quote, get in back in a minute. Significantly lower costs. I generally will buy as many years as I expect to own the car matched with the miles I expect to drive. I buy the best version which is coverage for everything EXCEPT for what is mentioned as not covered. That is much better than one that states only what they DO cover. I get a $0 deductible so I don't have to do mental mind games with myself as to whether I should get something fixed or 'deal with it' now, or wait until I have other things wrong to 'make it worthwhile'. Every extended warranty I have had has 'paid for itself'.
