a little off topic: why ac piston engine can't use auto gas?

nottobe wrote:

I know avgas is 100 octane with lead, but i wonder why aviation engines can
not be designed to use auto gas? i heard that avgas would be tripling the price in a few years, and possibly oil companies will terminate their avgas production......

Some aircraft engines can use auto fuel under a STC(Supplemental Type Certificate) letter from the FAA. Cessna 150, 172, 182 and many other qualify for auto fuel use. The problem is that aircraft operate in a wide area of temperatures and pressures, this effects the anti-knock qualities of the fuel which is formulated for auto use. Each engine has to be certified for auto fuel use and may include certain restrictions such as temperature, maximum altitude and/or a change in the maintenance schedule.

can the engines be designed to overcome these issues?
and if not, aviation diesel engines that use Jet A will be the next generation

nottobe wrote:

can the engines be designed to overcome these issues?
and if not, aviation diesel engines that use Jet A will be the next generation

I think so but like so many things in aviation, it's all about money, it just takes time. Long ago, we used red 80 octane fuel in aircraft, it was replaced with the blue 100LL(Low Lead) that's common today. In time, we will transition to another fuel.