Javelin, you are years out of date.
I've done 3˝hrs behind or in front of two Rotax engines today, one was generating 100hp, burning less than 3gph, and is available fully certified.
The other would, admittedly fit your description adequately, but still propels an aeroplane through the sky adequately, and I've owned it and the attached aeroplane for 5 years without any more problems than you'd get on the normal ludicrously overpriced Lycontintental 50 year old designs.
G