If the aircraft you are referring to is a 152 then if it were not for the US liability problem killing most certified aircraft manufacture for 30+ years it would have been superseded (and scraped) long ago. We should have had the VLA/LSA revolution in the 70’s not the 10’s.
A friend of mine is designing a 2 seat machine which will lift two adults, 4 hours of fuel and bags on 50 ish hp using modern techniques. I understand there are other people working on similar projects. If, as is expected by some, fuel will double in the next few years, such aircraft will be the flying machines for the common pilot as 18 lph will be as excessive as 33lph is now. Fuel is by far the biggest cost of running my MCR.
Rod1