Many can dealers that knows the values of cryptocurrency, especially Bitcoin do accept bitcoin as a means of payment secretly...in my country Many car dealers and building engineers have been accepting payment with bitcoin for long time, so it's not longer a new thing...but the issues is that they're not making it official to the public to know...but if they found out that you're interested to buy their products, they will give you options of payment and cryptocurrency or bitcoin is one of the first options that will be given.....
So, it depends on the country you reside..even in my country you they're some mall that you can make a payment of what you bought with cryptocurrencies, depending on the location the mall is situated...
I think that it'll be quit difficult for cryptocurrency to be accepted as large payments for expensive items like cars and houses, aside from regulation matters, the fear of exposing yourself publicly that you hold a lot of cryptocurrency is a problem because either buyers or sellers can be targeted. It is unfortunate that we hear about wrench attacks on crypto holders and I believe that it would discourage a lot of holders who would like to spend theirs if they feel that they can be traced, the same thing goes for sellers too. For now a lot of crypto holders prefer their privacy and you cannot blame them, although I'm happy that some dealerships accepts Bitcoin either openly or secretly so if you're bold to spend yours you can locate where cryptocurrency are accepted.
The payment thing have a lot to do with reputation thing, off course I have heard a lot of instances that guy's buying cars and paying with Bitcoin, so I don't see any problem with that. It all depends on the trust level between the car dealer and the buyers. Once they can establish an agreement on currency and method of payment that lowers the fees on the transaction as much as possible, it creates that contract.
Most celebrities over here are buying most cars in billions of my currency, and the payment is not through the fiat financial system.