It sounds like it has the same disadvantages as a gas turbine, then. It would have been helpful if they had contrasted it to a gas turbine instead of to a piston engine. Theoretically, a gas turbine has huge advantages over a normal ICE. Yet, there aren't any cars powered by gas turbines...
That's significantly because turbines have vastly worse throttle response than reciprocating piston engines though.
This does look like nothing more than a new turbine design, I agree, but frankly a turbine driving a generator and a battery is by far the most energy efficient means of running a vehicle from a combustion fuel source anyway; that's been the case for years, and if this tech helps get us to that point then all the better.
Gas turbines have by far the best power-to-weight ratio of anything short of a rocket motor. And large gas turbines can be extremely efficient.
But they're expensive and the efficiency advantage largely disappears as they're scaled down to a size appropriate to power a car.
Probably the fundamental reason we don't see production gas turbine cars is that there are cheaper and less technically risky ways to remove weight from a car, and weight savings often isn't even the cheapest way to improve efficiency.
Sadly, they don't seem to have taken the market by storm even though they claim to double to fuel efficiency of a 40 ft bus. Unless fuel prices go up significantly, factors other than fuel efficiency will probably stand in their way (questions of reliability and supply chain are mentioned).
It actually reminded me of another turbine-like engine I had seen a while back. They had tested it on chainsaws where the reduced vibration was desirable. I guess hybrid applications are mentioned because its trendy. I'm sure there are tons of other potential applications, just can't chase everything.
Basically: This is only appropriate for use in hybrid engines, as the range of efficiency is very narrow.
That said, if it works, this would be terrific for further upping the efficiency of hybrids.