Automotive EFI systems are smart enough to detect the lean condition and correct for it, outboards may not be. Cars also don't typically sit for months at a time with the same fuel.
In the event of a big failure, car engines will burn a piston from pinging, but it's rare. With knock sensors and all of the redundant engine management, it's very hard to do, unless it's turbocharged, those are way more prone to it. Low speed preignition is a big problem on turbo direct injected engines, I still don't think they have figured out a way to stop it, they say the right kind of oil helps. Ford went back to port fuel injectors in addition to GDI, which also helps with intake valve coking, and may lessen pinging.
Ethanol is very resistant to pinging (E85 is like 108 octane), but it has less potential energy, requires more of it to do the same amount of work. Flex fuel vehicles have ethanol sensors that constantly check ethanol content and adjust fueling as necessary. If you ran it in a typical car engine, the worst that would happen would be crappy running, and a lean code would set from the PCM dumping fuel while trying to correct the lean condition. The knock sensors should dial back timing way before engine damage can occur.
It's also worth noting that marine engines run at 100% load 90% of the time, that would be like a car going up a steep grade running as fast as it can without losing speed, engine damage is way more likely to occur in those conditions.