When your life depends on it, you're more likely to choose the engine that has all of the kinks worked out, has proven reliability, and where the failure modes are pretty well known.
* the avionics have improved immensely (solid state gyro instead of vacuum-pump driven mechanical gyro, for example, GPS, etc.)
* in tandem with that, cockpits have improved ("glass cockpit" with two or more huge screens instead of the traditional 6-pack of small instruments)
* there's been innovation and progress in materials (composite instead of aluminium)
But the engines are still the old dinosaurs from the 60s :-(
That's one reason many pilots are watching battery tech and electric engines with interest (so far, the specific energy of batteries is way too low, giving an hour of endurance if you're lucky).
There are several companies making unleaded fuel undergoing certification testing right now. It's not clear which one (if any) will "win", but I have high hopes that one of them will.
In terms of efficiency, that airplane does >200mph at better than 15mpg. That's not too bad, IMO. Better engine management tech would get me an easier workload as a pilot, but I don't expect it would yield meaningfully more power or efficiency, unless you were to raise the compression ratio (which typically requires higher octane fuel, and existing 100LL fuel is already pushing it, with a rich detonation performance of roughly 130 octane due to the benefits of TEL)