insert `extended warranty` in the search engine on this site and carefully read posts.

also do a google search on extended warranty.

may also want to go to www.ftc.gov

and before you buy - if you decide to buy - an extended warranty get and read all the documentation particularly about exclusions.

you can/may negotiate price on an extended warranty.

I personally would never buy an extended warranty, I would set aside money for eventual repairs. If the in-laws are to be trusted you have a pretty good idea on the track record of this individual vehicle.