BRP claims up to 30 percent lower consumption than like-power aircraft engines.
I don't see how they can deliver a 30% better SFC than another petrol engine operated at peak EGT or LOP.
The old Lycos already outperform any
petrol car engine, of any era, on SFC. A higher-RPM engine like a Rotax should be slightly worse than a low-RPM direct-driven engine due to greater friction losses.