So, I am sitting in a cafe, having coffee. My car is sitting in a carpark, having... nothing. Maybe that's how it should be, but maybe it could use the time wisely and go to auto-wash, recharge itself (that's same as "refuel" for old-timers), maybe help someone get to a grocery store in the meantime.
To make that happen the car would need to be able to pay and get paid for stuff. It's too easy to cheat a car though - it's still dumb, even if it's smart. So, we'd have to use a trustless payment method that's impossible to fake. Enter #IOTA or whatever is your favourite scaleable crypto. 😉