Definitely I would rent a car with bitcoin, considering the platfrom is a reputable one with good customer support for its users as well a physical company where one can easily connect with the team in a certain country. Barriers like this is what bitcoin was created to solve so people would be able to control their cash at any point in time. Although I haven't tried out renting a car before but if eventually I end up needing one for a quick purpose, definitely I would check out for platform like this.
Good customer support is going to be difficult, not saying it's impossible but if you think about it, companies that launch thinking about accepting crypto instead of regular payments don't usually have the customers best interests in mind, rather could be taken as a matter of "it's easier" instead, and what's easier in the support area is to not offer support or not offer a complete support experience. Maybe they'll enable a suggestion box for you to submit your complaint to and not much else.
On the other hand, a company that launches and has regular means to get paid, but also decides to include crypto might have a better chance to have good support. But that's just my opinion.