&gt; We need new engines.  My 1966 Cessna 172 required leaded AV gas, which is as rare<p>Frankly, not an arena where NASA is needed.<p>In Europe turbo-diesels are popular for retrofit because they happily consume Avtur ( kerosene ) which is cheap and plentiful.  I&#x27;ve seen a few 172s with Thielert TD engines. There was also a project to install a TP100 turboprop but I&#x27;m not sure how that&#x27;s progressing.<p>The fact that Cessna is still hawking a derivative of a 1947 airframe with an engine that isn&#x27;t much fresher is more indicative of their attitude than any lack of advances in low-end aerodynamics.  Look at the Stallion to see what they could be delivering, instead:<p><a href="http:&#x2F;&#x2F;www.aircraftdesigns.com&#x2F;specifications.html" rel="nofollow">http:&#x2F;&#x2F;www.aircraftdesigns.com&#x2F;specifications.html</a><p>200 kts for 2,200 nm, seating for four people.<p>At the small-end we need disruption of the big-three ( Cessna, Piper, Beech ) manufacturers, with technology that exists but they don&#x27;t bring to market.   Projects such as the 177 and Starship show that they had the technology, they just didn&#x27;t have the incentive to change.